Quote:
Mostly I play solo PvE.
What is your playstyle? Do you drain-tank, drain-hunt, or something else? It helps to know how you fight, so we can suggest talents appropriate...
Quote:
what are the pros and cons of the other trees? And what are the better low-level talents in those trees?
Demonology is defensive (at least until you get down into Demonic Sacrifice and Master Demonlogist). Destruction is offensive. The only really bad talents in Demonology are Master Conjurer and Improved Enslave, and you can't get those while specced UA. For Destro, avoid Cataclysm and Aftermath (yes, they both look good, but Impr. Shadow Bolt and Bane are MUCH better choices), and you probably want to avoid Improved Firebolt and Impr. Lash of Pain as well, but those are a little more negotiable.
It boils down to how you want to play. Demonology will improve your durability, while Destruction will let you kill stuff quicker. Destro is better if you want to do instances, as Aff.'s DoTs tend to not help much on the shorter trash fights (although, you will SHINE on bosses). Demo will help you last longer against mobs, so if you drain-tank I'd suggest going down there.
Try one, and if it doesn't suit you, it'll just cost a few gold to respec and try something else. :)