Yeah, LOTR seems the obvious
because it is awesome.
Garth Nix e.g. Sabriel, Abhorsen, Lirael etc were alright.
Eragon was good, but I didn't like the others in the series.
Narnia ftw
Twilight fails.
Harry Potter was pretty good.
I also liked the Books Of Pellinor series? I can't remember the author, but pretty damn good.
And, as a random sideline, the Noughts And Crosses series, by Malorie Blackman. Although admittedly the first one blew me away and the others sort of limped through it a little.
And I really enjoyed the Alex Ryder ones by Anthony Horowitz until I was like 13. I haven't read the very new ones though, as they sort of lose their appeal once you've grown up a little.