While I think most of these are good answers, personally I'd have to think Giannis is the favorite at this point.
I think the crazy thing about that is, he finished 7th in MIP his 2nd season, 3rd his 3rd season, then if he finished 1st this year, I think that would be a pretty amazing climb.
Granted, I've never really paid close attention to MIP voting before, but to show that kind of improvement and to get an increasing amount of 1st place votes in 3 straight years, I think that's pretty impressive.
And it's not just increased minutes improving his numbers, but all his advanced and per-36 stats are improving every year as well. I'm definitely impressed by the consistent growth he's shown.
At this rate, he'll probably be averagin 32/12/10/3/3 next year and become the first player to win back-to-back MIP awards, now that would be something.