I prefer frozen rodents from Rodent Pro or any similar vendor because they pose no threat of internal parasites. I also find frozen rodents preferable because you don't need to feed or house them and put up with awful smells or run to the pet store once a week. All you need are some ziploc baggies and some freezer space.

If your snake is used to eating live prey but you want to switch to frozen/thawed, you can transition him by giving him a fresh-killed rodent. It'll still have that live prey scent, and if you offer it right after killing it, it'll still be close to live temperature. Once you get the snake to take that, you can transition to frozen/thawed by scenting the thawed rodent with a live rodent or with a product like "Mouse Maker." Eventually, you'll be able to offer the thawed rodent without having to scent it. Of course, you'll always need to warm the rodent to somewhere close to a live rodent's body temperature. I do this by placing it under a heat lamp for a couple of minutes before offering it to the snake.