I have clocked up many thousands of hours on a variety of Walker mowers.A good used diesel side discharge model would be my choice. They are very solidly built. Quality Eaton hydros and fabricated decks.Belt drive 52" deck is virtually unbreakable and will adjust up to 4" cutting height. Can cut on slopes to the point where I worry about the engine oil pickup. Gear drive decks are a bit fragile for rough mowing.Kubota diesel model is the pick of engines. It is torquey and reliable. Not so impressed with the Kohler engined models. Air cooled engines are problematic in the hot weather we get in southern Australian summers. Cooked one recently despite all care and had to fight to get warranty repair. Walker are putting out some cheaper models (MB) to compete on the home owner market but these are not as durable and have cheaper hydros.Have no experience with other ZTR's. Other brands may well be as good or better. Recently looked at a Kubota and they look good. Quite a bit heavier than a Walker, plenty of ground speed, fabricated deck. As always it all depends on a lot of variables such as how much use it will get and in what conditions.