I've had very good luck with buying/owning/operating used tractors...and in fact have three of them. Today's diesel engines are very reliable and good for hundreds and hundreds of hours. However, alternators, water pumps, hydraulic pumps, etc. do fail and can make the tractor unusable for the time you can't get parts.
With parts availability assured and good quality used tractors, I wouldn't even consider buying a new tractor myself,
