Advise on motor selection for use with G320’s

I am putting together my first CNC project and I have been scouring
ebay looking for a couple of DC servo motors to use with my G320's
from our friends at geckodrive.com.

What type of motors do I NOT want? I see a lot of info on CNC
conversions with the G320's, good info on sizing of a motor, but
I am
looking for the "Top 10 ways to get stuck with a motor you
can't use
for your project" list.

I know I can put an encoder on most motors if needed. What about
brush vs. brushless? Any brands to avoid?

The project is a 4'x8' plasma cutter.

Thanks,

Steve