well, obviously everyone starts out with Tiesto or Armin van Buuren. now, if you want something a little more classy, go for Ferry Corsten, Blank & Jones or Thrillseekers.
I'm not that big on Trance myself, but start with those three and see where it takes you.
Bt is one of my favorites, hybrid also produces a trance sound, more breaks orienrtated tho rather than 4/4. Also breeder has done some absolute classics...
google "crystal clouds", thats a trance and progressive forum/website with free downloads by many top DJ's in the genre. they survive on donations so if you like what you hear, give them some feedback and donate, either way theres plenty of mixes to download and listen to!!, so as soon as you find a sound your after, have a go yourself.....I'm a big trance fan, and i know trance itself has a massive stereotype, but over the last few years there has been many new sounds comin out so don't be afraid to break the mould of the genre, this could be said about many genres i spose.....My favs....theres so many, search labels such as "alter ego records", "armada", "anjuna"......artists..,robert nickson, marcus schultz, cressida, rank 1, sean tyas......etc., good luck..!