Choosing a Bow for your Ranger

Armor Penetration

Armor Penetration is a percentage adjustment of the Armor Level of the target. For example, 10% Armor Penetration means that the base Armor Level of the target is multiplied by 90% to determine the effective Armor Level. Armor Penetration comes in two varieties, Base AP and Bonus AP. Base AP comes from the Strength attribute, Penetrating Attack, Penetrating Blow, and certain Air Magic spells, among other things. Bonus AP comes from Judge's Insight and the Sundering weapon mod. Only the highest value of base AP applies, but all values of bonus AP stack on top of the Base AP.

The maximum armor penetration that a Ranger can have with a bow attack is 50%, from a Sundering bowstring (10% bonus AP) plus Judge's Insight (20% bonus AP) while using a Penetrating Attack (20% base AP).

Bow Classes

There are 5 classes of bows in Guild Wars, which I will name according to the most "common" type:

Flatbow - includes some Ascalon Bows, Flatbows, and the Ithas Bow
Longbow - includes some Ascalon Bows, Longbows, and Storm Bows
Horn Bow - includes some Ascalon Bows, Horn Bow, Ivory Bows, and Shadow Bows
Composite Bow - includes some Ascalon Bows, Composite Bows, Dead Bows, Recurve Bow, and Eternal Bows
Short Bow - includes some Ascalon Bows, Half Moon Bows, and Short Bows.

In addition, each bow class differs in the following characteristics:

Range
Refire Rate
Arc Size
Appearance
Armor Penetration (special)

Ascalon Bows
Ascalon Bows given by the collectors tend to imitate one of the above bow classes. The appearance of the bow remains as a Flatbow/Longbow, but it can be either a Flatbow, a Long bow, a Composite Bow, or a Short bow as far as range, arrow speed, and rate of fire. You'll have to experiment to find out which one it is.

Damage Range

Bows do various ranges of damage based on their quality. Note that a Shortbow and a Longbow can do the exact same amount of damage. The type of bow does not influence the damage rating of the bow. The maximum damage range that a bow can have is 15-28. There are rumors of 16-28 bows out there, but 15-28 is the maximum you can expect.

In order to take advantage of the damage range listed on a bow, one needs to meet the prerequisite amount of Marksmanship required by the bow. Otherwise, the bow will behave as a Level 5 bow of the same type, with greatly reduced damage. The actual base damage value varies and it is hidden, but it will be the same as if the bow was dropped by a Level 5 enemy.

Bows with lower Marksmanship requirements do NOT do more damage if you exceed the Marksmanship requirement by a greater amount. There are no bows with a requirement of Beast Mastery or Wilderness Survival, and the only bow with an Expertise requirement is the Ithas Bow (which has both an Expertise and Marksmanship requirement).

Range

Most bows can be lumped into three categories of ranges:

Short range - Just within the "Aggro circle" on the Radar. The only bow class with this range is the Short Bow class.
Medium range - Up to "Casting Range", which is just beyond the "Aggro circle" on the Radar. The Horn Bow and Composite Bow classes dwell in this range, and it is similar in range to all Wand/Staff weapons.
Long range - Up to 1.5 times the distance of the "Aggro Circle" on the Radar. The Longbow and Flatbow classes are in this range.

These ranges are based on flat terrain. Being on higher ground than your target will increase the range of your bow, while being on lower ground decreases the range of your bow.

Refire Rate

The first shot that you fire from a bow will always be 2.0 seconds in duration. However, after that initial shot, the rate of refire differs between the bow classes. There are 3 rates of refire:

Fast - approximately 2.0 seconds between shots. The Short Bow and Flatbow classes have the Fast refire rate.
Medium - approximately 2.5 seconds between shots. The Longbow and Composite Bow classes have the Medium refire rate.
Slow - approximately 2.7 seconds between shots. The Horn Bow class has the slow refire rate.

Arc Size

Arc size determines both Arrow Speed (how fast an arrow takes to hit its target) and accuracy (leeway of the target dodging shots):

High arc - Flatbows have the highest arc out of all of the bow classes. Thus, the Flatbow class is the least accurate against moving targets at range.
Normal arc - Horn Bows, Longbows, and Short Bows all have a normal arc. Note that because a Shortbow has such a small range, the Normal Arc doesn't really have much of an appreciable effect on arrow speed.
Low arc - The Composite Bow class has the lowest Arc, and thus has the shortest time to target and fastest arrow speed, making Composite Bows the most accurate bow class.

Called Shot, Favorable Winds, and Read the Wind will make the Arc size approximately the same as the Low arc of a Composite Bow.

Armor Penetration

Horn Bows, Ivory Bows, and Shadow Bows have 10% Armor Penetration, according to a couple of sources. This compensates for their slightly slower attack speed. With speed increases, these bows can potentially do the most damage, especially on armored targets. For general purpose use, and for Bow skills, however, a Short bow is probably better.

What's the "best bow"?

There's no such thing as the "best bow". Each bow class has strengths and weaknesses. Short bows are great for overall damage, but are lacking in Range. Flatbows can also deal a similar amount of damage, but they are inaccurate at long range. Longbows are slow, but have a long range and normal arc. Composite bows are guaranteed to hit, but are merely average in other stats. Horn Bows do the most damage per single shot, but have the slowest refire rate of all the bows.

My advice? Use a long range bow for pulling/luring, a short range bow for close combat, and a composite bow for interrupting.

Bow Upgrades

There are two kinds of upgrades that you can apply to bows: Bowstrings, and Bow Grips. Each upgrade adds something to the name of the bow, and can be applied to any quality of item, from mundane to magical blue to rare purple/gold. You are more likely to find Purple and Gold items that are already upgraded with a bowstring or bow grip. You can only use one Bowstring and one Bow Grip to upgrade your bow. A new Bowstring or Bow Grip will overwrite the old mod, and you will lose the old mod permanently.

Upgrades can often be salvaged from a bow using an Expert Salvage Kit. Expert Salvage Kits have a random chance of extracting either the Bowstring or the Bow Grip.

Bowstrings

Bowstrings add "prefix" upgrades to a bow and include the following:

Ebon - Changes the bow damage from Piercing to Earth
Fiery - Changes the bow damage from Piercing to Fire
Icy - Changes the bow damage from Piercing to Cold
Poisoner's - Lengthens the duration of Poison by 33%
Shocking - Changes the bow damage from Piercing to Lightning
Sundering - has a random (5-10%) chance of having 10% armor penetration
Vampiric - -1 Health Degen, Steal life on hit (1-5 points)
Zealous - -1 Energy Regen, +1 Energy per attack

The only bowstring that doesn't see much use is the Sundering bowstring, due to the small percent chance of actually applying the effect. The elemental bowstrings are popular with Ranger/Elementalists who wish to take advantage of the Conjure lines. Zealous bowstrings are popular with Barrage spammers, as each arrow reclaims one point of energy. With a fast-firing bow and perhaps certain attack speed stances, zealous bows provide a quick method of Energy regeneration, especially for folks who don't use sustained enchantments. Poisoner's bowstrings are always popular among Rangers who use Poison Arrow and Apply Poison. The Vampiric bowstring is useful for a "bow switch", as the -1 Health degen can hurt over longterm use.

There is a rumor that the Shocking bowstring gives 25% armor penetration. This is not true, but it is based on the fact that most Air Magic spells have 25% armor penetration. Shocking bowstrings only change your damage to Lightning.

Bow Grips

Bow Grips add "suffix" upgrades to a bow, and include the following:

Of Defense - adds Armor +4-5

Of Shelter - adds Armor +4-7 (vs. physical attacks)
Of Warding - adds Armor +4-7 (vs. elemental attacks)
Of Charrslaying - adds Damage +10-20% (vs. Charr)
Of Deathbane - adds Damage +10-20% (vs. Undead)
Of Dwarfslaying - adds Damage +10-20% (vs. Dwarves)
Of Giantslaying - adds Damage +10-20% (vs. Giants)
Of Pruning - adds Damage +10-20% (vs. Plants)
Of Skeletonslaying - adds Damage +10-20% (vs. Skeletons)
Of Tenguslaying - adds Damage +10-20% (vs. Tengu)
Of Trollslaying - adds Damage +10-20% (vs. Troll)
Of Enchanting - Enchantments last 10-20% longer
Of Fortitude - adds Health +20-30
Of Marksmanship - adds +1 Marksmanship (10-20% chance while using skills)

Fortitude and Defense/Shelter seem to be the most popular Bow Grips. Some Rangers who are also secondary spellcasters tend to prefer the Bow Grip of Enchanting.

Which is the better bowgrip, "Of Defense" or "Of Fortitude"?

There's an ongoing debate on which bowgrip is better for a Ranger in the long run. The bowgrip of popular choice seems to be a Bowgrip of Fortitude, as seen by the enormously inflated prices for a perfect Health +30 version. However, if you look at the numbers, Bowgrip of Defense with an Armor +5 reduces incoming damage to 91.7% of normal, which means about a 9% benefit. Even if the Fortitude grip is perfect at +30 HP, the benefit from the Fortitude grip amounts to about 5% to 7%, meaning that based on Armor Level alone, the Bowgrip of Defense looks like a better choice.

However, there are several situations in which a Bowgrip of Defense does not give any benefit. For example, Conditions and Hexes that apply Health Degeneration ignore armor, as do most Necromancer and Mesmer damaging spells. Also, Death Penalty applies to your base Health and Energy, while bonuses to Health and Energy remain the same. Thus, while the Bowgrip of Defense Armor bonus remains static, the utility of the Bowgrip of Fortitude actually increases as your Death Penalty goes up, by virtue of the fact that it is not reduced by Death Penalty, giving you a higher overall Health.

Still, it is FAR easier to find a cheap Armor +5 Bowgrip of Defense than it is to find a high level or perfect Bowgrip of Fortitude. Mostly, it boils down to personal preference. The Fortitude bonus always applies, regardless of the kind of damage that you take, but the Defense bonus provides a better long-term benefit.

There are also bowgrips of Shelter and Warding. Having any bowgrip is better than having no bowgrip, but these only protect against physical damage and elemental damage respectively. Neither protect against non-elemental damage like Light, Chaos, or Dark damage from wands and staves (the Bowgrip of Defense does protect against these types), and have the same caveats as stated for the Bowgrip of Defense above.