chik, there are probably authors out there that are just as good, but Prufrock's love writes the type of stories I like. I highly recommend Pascal's Wager. Great explanations for Scully's pregnancy, the paternity and Mulder's return.
For angst, The Darkest Hour is wonderful. I also like Agunah I and II, A Moment in the Sun, the Hiraeth Series (a WIP... don't object yet, Rio! Each individual chapter is a story in itself. You aren't left hanging while waiting for the next installment), War Stories and Maple Hair as a short fic, Touching Velvet, and the Cycles Series. I haven't had time to read the few left that I didn't name, LOL!
If you have time, read Parabiosis by Penumbra, my other favorite author. It's long but really worth it. I love her Mulder and Scully. She also wrote the best post Orison story, Black Hole Season. Another great one is Contact High, a post Field Trip story.