Dealer, Dealer, Dealer
Anyone can make a good tractor. Anything that is made will have problems at some point and you need a good dealer network to get you the needed parts and or service to keep going.
We farm over 2,300 acres of row crop as well as about 200 acres of hay and a small amount of custom work.
4010, 4020, 4630, (2) 4650s, all green and the newest are the 4650s which are 1985 models - - - all look like and run like new.
About 4 or 5 years ago we traded the 8630 for a 1985 9170 ( red ) and we have been very happy with it. We spend winter months on prevenitive maintance - - - 2 years ago a head gasket on one of the 4650s last year new exhaust manifold connections and adjusted the valves on the 9170 also replaced a brake line.
The 4020 and 4630 were repainted and a new cab interior on the 4630 two winters ago. New clutch on the 4630 about 4 years ago ( about 12,000 hours on the one we replaced )
We have about 10 John Deere dealers with in 30 miles and 1 International/Case and one New Holland so it goes back to Dealer, Dealer, Dealer!