What type of computer are you using? Do you have to go USB? Is it a laptop or desktop.
I just spent the last two years building a 24 track digital studio and can fill you in on the trials and tribulations of compatibility and processing power.
In general, almost all usb mixers are a 2x2 interface (1 stereo channel in, 1 stereo channel out - in case you were going to ask.
If you have adat capability I would recommend the Allen and Heath Zed16. It will allow you record all sixteen tracks to individual tracks in your DAW.
If you have firewire I would recommend the Saffire Pro 40l. It has 8 mic inputs and totals up to 20 including the digital ins. It can record up to 18 simultaneously over the firewire. This unit has some of the best routing options and monitoring that I have seen in over 15 years of recording.
If you MUST have USB connectivity, I would recommend the Prosonus
Audiobox 1818vsl. It can record up to 20 channels simultaneously (when including digital inputs). It is USB 2.0 and has awesome routing options and a virtual mixer that you can use to control FOH sound from the stage.
Both of the above units range in price from 300-500 canadian dollars.
If you have any other questions please feel free to contact me.
Jeff