Warlock talents

depends on what you want to do:
Affliction: good for leveling, curse everything and let your Voidwalker aggro everything. Most Mana efficient, so less downtime. Can be a little complicated to play, with its DoT rotations, but you will pick it up fast. Good talents are Nightfall (instant Shadow Bolts) Siphon Life ( a curse that drains health) Dark Pact ( drains pets mana, returns it to you), and In proved Corruption ( makes it insta cast)
Demonolgy: Increases your durability and increases the power of your utility spells (Hearthstone, Spellstone,Firestone, Soulsone, etc.) Buffs your demons and allows you to summon them instantly with less mana. Good talents are Fel Stamina ( decreases Spirit, a useless lock stat thanks to Life Tap and increases Stamina which we can tap to give us mana) Soul link ( shares 30% of damage with demon) and Master Demonoligst ( gives you buffs depending on your pet). This tree is really durable, and you pretty much never die in PvE. If you do, you just pop up again with your Soulstone. You can solo a lot with this spec, good for questing.
Destruction: Destruction makes you play a little like a Mage, with increased burst damage and crits. However, if you take this tree, be warned. Mages will be perferred over you in this role, as they can do more damage using less mana. You still have your DoT's however, so your damage will be pretty much the same. This is the spam Shadow Bolt/ Immolate&Conflagerate spec. Good talents are Destructive Reach ( adds range to destructo spells) Conflagerate ( companion to Immolate, causes direct damage if the target is affected by Immolate) and Shadowburn (gives you an insta cast DD spell.) Good for raiding, because you can Life Tap and DPS longer. Bad leveling spell, because its mana efficiency is horrible.

The "best" tree depends on your playstyle. If you can handle complex DoT rotations and great efficiency, choose Affliction. If you want survivabilty choose Demonolgly, but be warned, if you are without a demon, you are pretty helpless. If you want to blow crap up, and don't care about downtime, choose Destruction. I think that Affiliction is the fastest leveling spec, but if you don't like complex spell rotations you can choose deamonolgy, the second fastest. If you cannot stand either, choose destruction. It's you playstyle and your choice.