Guys like Fedor. His style is the most fun to watch.
I agree, really good Sambo fighters are awesome to watch, everyone always says "they are so sloppy" but they just don't know what they are looking at, there is a reason Fedor is the least hit fighter in MMA and why Khabib rarely gets hit. Fedor and Khabib both have great head movement, they parry punches with their own and are great at punching into the clinch so their opponents can't counter them. My next favorite styles are Muay Thai/BJJ like Shogun and Wanderlei and Wrestling/BJJ like Weidman.
I don't have a favorite style per se, but I do tend to enjoy someone who is a real expert in one area rather than pretty good in all areas (I.e. Ronda Rousey, Khabib).
The striker with amazing sprawl that destroys all that try to hump in and win on points
The Wrestler or BJJ ground specialist with lethal GNP
The black Mamba submission specialist that once he has you down youre done
Anyone that goes into beast mode, especially after losing the first 2 rounds and they get the KO vs fighting to lose.
Anyone that throws the flying knee after being repeatedly taking down against a wrestler that's been telegraphing it ALL night.