Considering Hamilton did the best with the worst care for much of the season and as the car got even slightly good and wasn't the best he outscored was it everyone for the 2nd half of the season, I'd put money on Hamilton.
But then, you'd have to see where the cars come in again this year. I'd be gobsmacked though if Hamilton didn't crush Button with no car difference between them.
I don't doubt Schumy's ability in the slightest, if the cars up there with the best he'll have a very good shot unless his neck plays a part in missing races or having to pull out entirely. But the team got ultra lucky with the first half of the season and most teams playing catch up, fair play they interpreted the rules better than others, if it wasn't for that I very much doubt they'd have won any titles last year. If they can carry that foreward and have a competitive car throughout is a big ask.