MM1: Elecman, since I've really liked him after I've played Power fighters and read MS Paint Masterpieces.
MM2: Metalman or Woodman...... Crap, can't choose... [though Mecha Dragon is great]
MM3: Shadowman, since he's the ONLY Robot Master I haven't beat with just the Mega Buster.... And he's badass. Sparkman is second, for his song that beats out ALL[/i] other stage musics.
MM4: Ringman or Pharoahman. Both songs are great, and I live the Ringman fight....
MM5: Stoneman. His music roxxorz.
MM6: buttfuckman- oops, this isn't Megacrap. Knightman is great, his song sucks htough. [but the awesome boss music makes up for it]
MM7: TURBOMAN. He's actually my second favorite robto master of all, hidden swift quirk.
MM8: Never played it, so I'll go with Tenguman, since i know what he's like.
MM&B: BURNERMAAAAAAAAAAAAANNNNNNNNNNN!!!!!! I love that guy... Yes, I beat him with just a mega buster/forte buster, and it was hard as hell, but I did it.. His song is strangely catchy, and his fight is VERY awsomezorz.
My list there. heh