What microphone less than $500-600 (USD) would you chose above all others and why. I might even go up to $700-750 if you have a good enough case.

Assume I've already got passable microphones for every conceivable function.

B.

ev re20.
shure sm7.
sennheiser md421.
beyerdynamic m160.
akg c414b tlii or uls.

you could do any record with just those, pretty much.

at4033
senn 421
beyer m88

Beyer M88 - Vocals, Bass

I'll add to the list:

AT 4047 - Kick Drum, Vocal

Electrovoice RE-55 - Drum Overheads, lots of other good things

Shure KSM 141. I'm in love with the two I got recently.

I scored a pair of KM85's a few years ago for $1000, so at $500 each - do they count?

If not, then my RCA 74B's, which I got for a couple hundred each.

electro-voice re20
shure sm7
beyerdynamic m160
josephson c42
akg c451

and, it's not a mic i "can't live without!" but i really dig the blue dragonfly for a lot of stuff. guitar amps, drum overheads/various percussion, certain singers...

atm25
m88
at4033
m160