Heavyweight
I've gotta go with Brock Lesnar here. I loved him in the WWE and that continued on into MMA. The guy's a force, no doubt. He may not be the most technically sound, but he's so freakishly strong, it just looks like he tosses people around the octagon. I'm really looking forward to his fight with Alistair Overeem, where he can (hopefully) pick up the win.
Light Heavyweight
Jon Jones, plain and simple. He's a star. At 24 years old, this guy could very well be the future of MMA. I mean, not only is he an amazing athlete with a great work ethic, nobody seems to know how to stop the guy. The way he has run through Shogun and Rampage astounds me and really speaks volumes about his abilities. His next fight against Machida looks to be a great test of his abilities, but he should win it.
Another reason I'm a big fan of Jones is just the way he behaves. He's laid back, not too full of himself, a family man. You couldn't really ask for a better guy to be the new "face" of the UFC and of MMA in general.
Middleweight
Close one here, it was almost Mayhem Miller, but there's only one guy who stacks up as my favorite -- Chael Sonnen. The guy is a loud mouth, but he's hilarious and he backs it up. The man cuts pro wrestling promos on Anderson Silva, a guy who is the pound-for-pound best fighter in the world, and then goes out and nearly takes the title from him, losing on a triangle choke in the fifth round. Then after a year of sitting out, he puts on the best performance of his career, demolishing Brian Stann, and challenges Silva AGAIN. There's nothing I don't love about the guy. I cannot wait for Sonnen - Silva II. To me, it just seems that Chael Sonnen has Anderson Silva's number. I don't want to get into a debate about that here, but he honestly seems like the only guy out there.
On top of all that, as much as he thinks his own shit doesn't stink, he's not one to shy away from fan interaction -- and I like that. The fans should be given some attention, some appreciation, shouldn't we?
Welterweight
Nick Diaz takes the cake here. He's the type of guy who a lot of fans hate, but I can't help but like him. As much of a jackass as he is outside of the cage, I've been impressed by his abilities inside of it. He's a damn good fighter and I'd love to see his fight with BJ Penn go his way, he should still be in line for GSP (or Condit, who I adore as well) after that. Plus, he's hilarious. His Youtube videos kill me.
Lightweight
Shinya Aoki. I've been a fan of him for a while now, but he's been on a tear for six straight fights. I'm hoping he gets some higher profile opponents soon, as I'd love to see him get the credit he truly deserves. Most fighters don't amaze me, but some of the stuff he does just floors me. You've gotta love a guy like that.
Featherweight
Jose Aldo. He, much like Aoki, amazes me. I'll never forget his quick knockout of Cub Swanson. He sprinted, planted the knee, and called it a day. The guy is so exciting to watch and it seems like he puts a lot of himself into fighting, it seems like it's his number one priority. I've watched some of his older fights and his strikes, under more relaxed rules, are even more lethal. That said, he's gotten so much better with time that I would not want to see him be allowed to soccer kick someone, for fear of him legitimately killing someone.
The guy's a star.
Bantamweight
Urijah Faber is one of my favorite fighters altogether, so this was an easy choice. He was the face of the WEC and one of the most dominant champions, if not THE most dominant champion, in the company's history. He's a likeable guy, but what most impresses me is the way he manhandled some great competition as champion. I loved some of his fights, but the Jens Pulver fight was stellar. They went five rounds and just slugged it out, they both showed massive amounts of heart there. Faber's always trying hard to get the win and I respect that.