Well, some of my personal favourites are the Three Worlds Cycle (no-one on this site seems to have read them though...), and the Discworld series. Also, if you like video game tie-ins, the Halo books are actually a really good read. And the Hungry Cities Chronicles by Phillip Reeve are pretty good. Phillip Pullman's His Dark Materials trilogy is great, as is the Deptford Mice series, and the Lord Of The Rings books (plus The Hobbit) are good, but a little overwhelming for a new reader.
Really though, we can't decide what you'll enjoy unless you tell us what genres you're into. I mean, my choices are mainly fantasy and sci-fi because that's what I like, but you might be interested in romance, comedy or historical novels for all we know (if you are, then I say anything by Mills and Boon publishers for the former, any Pratchett, Gaiman or Rankin for the middle, and the Sharpe series for the latter).
Also, I urge you to read the Twilight books. And yes, I am being 100% deadly serious here. The reason being not that you'll enjoy them, but that everyone denounces the series yet only about 5% (number pulled from my arse) of the people here who call it out have actually made any attempt to read the books or watch the films. So I say, read the books, please, and decide for yourself. If you don't like them then fair enough, you'll have earned that opinion, but until you at least give them a try you have absolutely no right to say whether they're good or bad. No right whatsoever. And that applies to everyone, about everything.