How many channels do you want? Are the mic's phantom powered condenser mics? What other kit are you going to be patching them with? What will you be feeding the mix to? Will you need to record them all at the same time? Will you need to record them on separate tracks?
If you are going for a computer based DAW (Digital Audio Workstation) you might be better off with a multi channel audio interface complete with mic preamps on each channel?
As far as Mixers go:
At the budget end there is Behringer. Cheap, but not terribly well regarded (even though actually their kit isn't that bad) - It's part engineering snobbery and part their quality rep from a few years back
Then take a look at Alesis - nice well built kit. Or Yamaha's MG range. both really great value for money
Probably then you are into Soundcraft/Mackie territory. I have a soundcraft Folio, because it's EQ is so nice.
An number of mixers now also give multi-channel audio over Firewire so you can plug them right into the DAW computer.
Of course, like all things in the pro-audio arena, the sky's the limit.
At the top of the tree there is Neve and SSL. I was talking to the guy who installed Bob Clearmountain's SSL. It cost one million dollars.