Nantz is the worst--a terrible, overrated PbP guy and an obnoxious toast-photo toting twit. It seems grimly appropriate that he announces a golf event at a club that's been synonymous at one time or another with racism, anti-Semitism, and misogyny. He's an aural vampire, sucking all the life out of every broadcast he does simply by virtue of being an egomaniacal doofus. I'm sure he's convinced himself that many of the people who tune to, say, KC vs. Buffalo do so because he's there doing that ridiculous, disingenuous 'hello friends' schtick. He'd step over his ostensible best friend if it meant another chance to hand over the Hunt trophy to some bigoted troglodyte of an NFL owner so he could stand there grinning his preppy Grinch's grin in the background while the owner drunkenly thanksssh all the fanzzz. He's never had chemistry with an NFL color guy.
Anyway, I no longer like Romo for many of the reasons others have cited--he talks too much, is insufferable during and after reviewable plays, and seldom provides any analysis of why the offense or defense had the edge on a given play. Collinsworth is a smug douche, but at least he brings some analytical acumen to the table.
I don't like Burkhardt and Olsen much, but that may be more because they seem like a big step down from Buck and Aikman. Olsen seems to get caught up in telling us why big star X just made a big play rather than get into the guts of what happened and why it worked (or didn't)--though when he does he's interesting. His voice, however, is reedy and chirpy, which doesn't help. Aikman remains my favorite color guy.
I think Ian Eagle, Greg Gumbel, and Kevin Harland are all vastly superior to Nantz. Michaels and Buck are, too, obviously.