I can't say it's the best since I've converted exactly 1 fridge to a kegerator, but I got a Danby DAR440BL on Craigslist. It was new, but dented a little on the back, so I got it for 65% off new price. But it was an older model, which was actually nice because the shelving on the door was screwed on so it was easy to remove (like 40 screws though). The newer models are molded on the door, so you have to dremel them off. Not really a big deal.
It was pretty easy to convert it, but since I have pin lock kegs, I did have to shave off the plastic pieces on the inside that would normally hold the shelves. Again, not a huge deal, but more work. If you have ball locks, probably not an issue.