Jeep, reading all the forums here, I'd have to agree that the least troublesome tractors are the older MFs. I have a '74 165, and except for some minor oil drips, that beast has never given me any problems and now at 3700 hrs. (I was once told you know when you're getting old when everything leaks or dries up).
I also have a new Mahindra 5525 with 7 hrs so nut much history yet. I've noticed that all newer tractors, regardless of what, seem to have a litany of problems that the older makes don't experience. Yes, the older ones are simpler in function, but more reliable. I hope my Mahindra makes it to at least 3700 as its the last tractor I'll probably by in my lifetime. And after that, I don't intend on shoveling coal in a furnace so I wont need a tractor.
I think the Chinese makes are probably the most to test one mechanical knowledge and patience.