I do find mullet best.
I don’t think there’s any competition between a 29 and 27.5 front end, I can’t think of a situation where a 27.5 is better except if you’re attempting to do 50to01 style spinny jibs, though I save that kind of stuff for the bmx/dj.
29 versus 27.5 rear, I’m a hair under 5 10 with decently long legs, but I’m a manny, whippy rider, it’s not necessarily steep where I run out of space, it’s when I’m throwing the bike around and hucking to bottom out. But yeah as many others say, 27.5 tips into turns more naturally and is nicer to move around, 29 does take the edges off of things.