I never had a favourite MMA fighter until I saw Tiequan Zhang's story in the current issue of Kung-Fu Magazine. He is a well known and respected sansho fighter in china that has made the move over to MMA, and seems to have fallen in love with Martial Arts all over again. Sansho doesnt have grappling so he added that to the skills he already had and has been very successful at it. On top of this love he currently holds an 18-1 record. Not to shabby in a sport where "Kung-fu doesn't work"
Fedor. He has so much respect for his opponents and the way he acts in and outside the ring/cage is very professional. Great documentary on him from a few years ago called "Fedor: Baddest man on the Planet". Definitely worth a watch!
I don't know that I have one absolute favorite, but I like Georges St. Pierre and Lyoto Machida for their high levels of skill, their dedication, their attitudes and their sportsmanship. The fact that they both have karate bases is a nice bonus, of course .