I like the small blast zones, but at the same time I really, really hate them. All a MK has to do is get you in a bad DIing situation because you were weaving, and boom, early kill. Wario cannot take early kills in this matchup... Getting them is nice, but getting them done sucks.
MK covers his weaknesses with strengths too well. Sure, he moves slow.. but you can't weave in and out of him because he is so fast and so ranged. He dies fast, but kills really early, and his kill moves land quite well... Which is a huge advantage. Back when I played GaW, who is hard pressed to actually land a kill move on MK, stages with large blast zones were actually prefered, because the extra life I got was worth the small survivability. I digress...
He covers his weaknesses too well with his adaptability, so a lot of stage choice is personal preferance. What PhantomX said about the platform is all too true, I like FD against MK. FD against MK WOULD be really solid, except stuffing your stuffs with his SL OOS is now a huge problem.
Sigh.