Overeem/Lashley (which is hilarious) and Mayhem/Shields. I suggest learning the controls with the heavyweights because it's not as fast paced. You can't take many shots though. Also, the harder difficulties are much more fun after you get the hang of it. The medium setting is really repetitive. Lashley will shoot over and over again. I usually play as Overeem vs Lashley, Overeem vs Overeem, Mayhem vs Shields, and Mayhem vs Mayhem.
I like it way better than Undisputed. Undisputed is way to robotic and more unrealistic. I can play EA's without having to spin the joystick 500 times in one fight. Playing EA's on Legend mode with classic controls has given me over 8 hours of fun so far. It's not perfect, but way better than Undisputed in my opinion. I also like that no matter what, if you take 5 shots from Overeem unblocked, you're about to get swarmed. That's how it would be in an actual fight. Also, it seems like the action is mixed up. Undisputed was way too easy and predictable.