Grabbed from Mowe's comments on #class-chat-n-tips
With sufficient AA, ranger becomes a top tier DPS by using Hail of Arrows (this is your biggest dps boost), Heartshot, Ancient: Burning Chaos, Sylvan Burn, and Frozen Wind. These all use mana quickly. If you handle mana regen with anything other than Beastlord's Focused Paragon then endurance usage becomes an issue. Min/maxed Trueshot is up for most of your fighting time and steadily draining 18 endurance a second.
Sirhopsalot suggestion: Team composition can be a bit built around the Ranger by using: Rng/Bst/Dru/Clr/(Wiz|Mag|Nec)/(Pal|SK). If Nec, then Pal can make up for the DPS that Nec lacks in quick kill situations and the Pal will greatly benefit from the Bst Paragon. Otherwise, with Wiz|Mag, SK might be a better choice since SK doesn't require the Bst mana regen and that opens it up to give it to the Wiz or Mag.