Not in any particular order.
1. Grey's Anatomy: I'm all about the Izzie/Alex. Plus individual character studies.
2. Veronica Mars: hell, if it's well-written, I'll read it. V/Lamb, V/Weevil, LoVe, Lilly/Logan, Mac/Cassidy, Mac/Weevil, occasionally Mac/Dick or Weevil/Logan if it's absolutely terrific. And individual character backstory. Sometimes the Kanecest.
3. Supernatural: Dean. DeanDeanDeanDeanDean. Dean/OFC if it's in character (even Dean/OMC), well-written Sam/Dean Wincest, all kinds of teen!chester and wee!chester.
4. Smallville: Chloe/Clark, Chloe/Oliver, Chloe/Jimmy, Chloe/Lex. Chloe/any guy, really. And Chloe/Clark/Lex because it is teh hotness.
5. Battlestar Galactica: Kara/Lee, Kara/Anders, Kara/Leoben, gen pieces, Kara/Helo, Kara/Lee/Helo (more of teh hotness).
6. Prison Break: Michael gen (character study stuff), the occasional Sara/Michael, and NON-SLASH Michael/Mahone mind-game stuff.
7. House: Chase gen (character study stuff), every once in a while some Chase slash (either H/Ch or W/Ch).
8. Farscape: John/Aeryn, John/Chiana.
9. Alias: really good Sark/Sydney, Sark/Irina, Sark/Nadia. OR Sark character study.
10. Firefly: Simon/Kaylee, Kaylee/Mal, Kaylee/Jayne, River/Mal, River/Jayne, every once in a while some Simon/River spacecest.
And then there is the crossover and crack!fic. Best stuff I've seen is Supernatural crossovers with House, Smallville, and Veronica Mars. There was also a terrific Veronica Mars/Farscape crossover where Veronica and Logan ended up on Moya.
Yeah. I need a life.