If these two aren't the standard bearers for 'glam metal', I don't know which two are. Style-wise, there were certainly flashier frontmen, but when you combine their flare with the popularity (notoriety?) they achieved, no others compare. They were without a doubt way more focused on the style over the substance (unless it's substance abuse). Form over function; sizzle over steak... pick however you want to phrase it, these guys will never be accused of dynamic range and power in their voice. However, there was a certain quality to both that allowed them to become way more than their chops would've dictated alone.
In the "who banged Pamela Anderson" category, Bret gets the edge for immortalizing it on tape forever (because, I'm sure Tommy didn't keep Pam all to himself).
I'll also give the vocal preference to Michaels. Sorry Vince, but Bret has got way more emotion, and diversity. Native Tongue wow'd the fuck out of me - soul and emotion just ooze from Bret on that album.