Well for starters, although it may be cool....it is not in the snakes best interest to eat live prey in captivity. They eat them in the wild, but in captivity all the conditions are altered so you can't even compare. Rodents can deliver a nasty bite, sometimes even deadly.
Now the next part. What criteria are you looking for. Do you want a small snake or a little snake? Active or more relaxed? Do you want to handle your snake? Snakes are solitary animals, they don't enjoy being handled, but some tolerate it better than others. If you can give us some more specifics, we can probably give you a better answer