DJ Tiesto
Armin Van Buuren
Showtek
Deadmau5
Aly & Fila
Ferry Corsten
Cosmic Gate
Paul Van Dyke
DJ Hixxy (More relaxed trance)
Infected Mushrooms (More of a hardcore-metal-trance thing)
Darude (Not really trance but still good)
Basshunter (Still not trance but ok)
Fridge - Paradise (Nu-Gray Mix)
Mark Norman - Restart
Simon Patterson - Thump (Original Mix)
Rank 1 - L.E.D There Be Light (Trance Energy '09 Anthem)
If you're looking for 1hr+ mixes then I'd get some of Tiestos live sets, Musemuplein + Innercity are two of the main ones, as well as In Search of Sunrise and In search of Sunrise Asia Disc 1+2. Armin has some good ones as well, mainly his Creamfields 2003 set mix, or his World Tour Spring 2004 one which is 3:15:17.
Get the Trance Energy 2009 discography, it's got some of the best ones i've ever heard. Also, if you can, get Godskitchen. Was at both of the aforementioned and they were some of the best nights of my life.
I have every song ever made by all the above artists/events. I'm a bit of a trance fan