Some flavor of combat build is generally taken to be the easiest build for leveling a rogue. But once you get to the middle of the tree, you face a decision: which weapon type to specialize in? Fist Weapons is easily eliminated, since there just aren't that many fist weapons, pre-raid. That leaves dagger, for 5% extra crit chance; sword, for a 5% chance to get an extra attack on doing damage with the sword; and mace, for +5 weapon skill and a 5% chance to stun the target for 3 seconds when doing damage with the mace.
While the swords play-style tends to revolve around Cheap Shot and Sinister Strike, dagger rogues lean more towards Ambush and Backstab. Why? Well, Sinister Strike is best with a high-average-damage (read: slow) weapon, and daggers are generally fast. And honestly, Backstab is a lot harder and more time-consuming to pull off in solo PvE than Sinister Strike. Sure, you can gouge and run through the mob, but it's so much easier to just stand there and whack it in the face with something big and sharp.