I have always found more info on used tractors at Tractorhouse.com
As for what units are reliable, just about all makes are good and reliable when new, a lot depends on the previous owner as to how reliable a used one is. I dont trust auction for used equipment as mostly they are getting rid of their headaches. Try to find someone who has a good used tractor that has discontinued use to to health reasons or retirement etc and keeps his tractor indoors when not using. A good clean tractor like that is a rare find but doable. Dealers would be my choice for used and make them give you at least a 90 day warranty, if they wont do that then pass on the tractor. Most tractors have to be at least 40 HP to have a cab so you are ok on that requirement. If you are looking to find a reasonably priced used tractor, you you may find that to be a pipe dream. That is why you find so many folks on here that bought new since used prices are practically as high as new with little to no warranty and if you are looking at financing, then you will pay higher rate for used. Many new are 0% interest for as much as 5 or 6 years with 0 to 30% down depending on your credit score.