I'm taking it that you are thinking more along the lines of high instances / raiding builds, if so there are really two (possibly three) main contenders. These are Combat daggers - 15/41/5 (i choose daggers over swords because i believe it generates a little bit more dps) and Mutilate raiding spec - 41/20/0.
Firstly Combat daggers is a fabulous build for all you rogues wanting to do the thing rogues do best - damage. Combat builds make is easy to sustain high dps without too much effort being put in, guaranteeing that you will be near the top if not the top of damage meters every raid. When it comes to this spec it really is a case of putting your gold in and away you go. Though with PvP it's another matter. This build is basically as useful as a plastic dagger up against plate armour - it wouldn't even compilment you with a gratifying noise. No when it comes to PvP 15/41/5 is possibly the worst build, perhaps second to 0/0/0.
Which brings me onto Mutilate. 41/20/0 is also a very good build when is comes to high dps in raids though it must be said you have to be more alert to pump out your max dps. Then comes the problem of poison immune bosses. I'm sure i don't need to tell all you rogues who have been specced Mutilate and come up against the Curator how useless he makes you feel. Luckly, there aren't that many poison immune bosses in most raids so this spec is still very viable and rewards the player with a warm fuzzy feeling similar to that of wetting yourself. On PvP while Combat builds perish Mutilate succeeds, producing a large artillery of tricks that will leave your prey in a pool of red liquid.
So, simple. If you haven't already worked it out heres a clue: -
If you are the player that is looking to max the damage meters, slice open all enemies with ease and be welcomed into most raid groups with kisses and hugs; a Combat build is for you... However if you are looking to succeed in PvE producing high dps that challenges you and keeps you alive, thinking one step ahead, while keeping a strong outlook on PvP - Mutilate is waiting.
Ark