There are many I've loved over the years including Cirie, Malcolm, Sandra, Courtney, Yul, Yau-Man, Earl, Aubry, Natalie A. just to name a few. But right now, after rewatching two of his seasons (still have Philippines to go), I might have to say Penner. He's fun to watch, both smart and a smart ass, talks back to Jeff, kicked ass in a challenge while injured, and seems, despite the smart ass-ness, just a good guy. Plus he was on Arrested Development which is a plus in my book.
I'm rewatching Nicaragua now. What a completely bananas season.