My take on it is this: none of the mics you have listed is a bad mic. In fact, as you have already noted, all have received glowing praise from other posters and published reviews.
Some are better at some applications than others (the MD421 for example). Some will sound at least good on more applications than others (IMHO like the SM7 for example). If you are looking for a mic as a general purpose mic to cover a lot of bases and do it well, then something like the SM7 is a "safer" bet than the MD421. The SM7 doesn't necessarily solo the best, but it works exceptionally well in a mix. That said, each mic will sound different on a particular voice (some better and some worse), and the only way to truly know which mic fits which voice the best is to try them. If you can't do such a shoot out, then you play the odds and pick the mic that is most likely to sound good on the most applications. If you want to listen to an album made using mostly an SM7, pick up Tim O'Regan's recent album (Jayhawks drummer). All the vocals, guitars and most of the other instruments were recorded with one of my SM7s (if I remember right, drum overheads were AT-4050s, kick was Audix D6, snare was SM-57).