The one that you enjoy playing. Now, I'm out before this turns to 50 pages long "x is better than y". If you can read and understand English, play with talents and see what each spec provides.
Yeah I wanna heal PvE. I would like to be versatile and be able to do both 10 or 25 man so it's easier for my guild. I don't know what the difference between tank heals and raid heals is.... I prefer direct heals, not HoTs. I would also prefer holy more than disc I suppose. I would rather be a healer healer than a buffer.