D-112 is the clear winner for me. That's exactly the sound I like and which will set well within a drum mix and band mix. Easy winner.
RE27 - very nice. Good definition and balance, just doesn't have the smooth low end of the D112
D2 - not bad, but would only use if had to.
MD421 - yikes. Not sure what you folks like about that sound! Really strange freq balance. I own an MD421 and honestly I only use it for toms or guitar cabs. I know it's a well loved mic, but I'm just not that fond of it.
Its too bad you didn't include the Audix D6. Would like to hear it alongside the lineup. I own a D6... it's kind of a one-trick pony, but it does that trick really well ("modern" kick sound). Overall, I think the D112 is the best kick mic.
Thanks so much for this useful comparison!!! Cheers!