Having only really seen UFC and Fedor/Mirko beating the tar out of people on HLs, here's my list:
1. Georges St. Pierre
2. Chuck Liddell (something is always going to happen in an Iceman fight)
3. Rich Franklin
4. Fedor
5. Cro Cop (I'm a mark for kicking peoples heads off)
6. Matt Hughes
7. BJ Penn
8. Karo (I'm a mark for Judo throws too)
9. Forrest Griffin (same as Liddell, something is always going to happen)
10. David Loiseau (just watched his fight at UFC53, so thats fresh in my mind, I love his elbows, even though he ran like a bitch against Rich)