Need advice on buying a riding mower

I don't want some else's headache and I need something durable to handle mowing around 3 acres of lawn with bumpy terrain and some slopes. My current machine is a 1997 Craftsman 50" with a 25hp Kohler with a little over 600 hours. It has needed a lot repairs over the nearly 20 years of using it. A lot has broken because of the weak design of a lot of the deck parts but I kept it going but now the engine is going to need major work because it's burning oil badly plus the frame has cracks. I don't want another machine with a Kohler engine nor a Craftsman (or whoever builds these things) if I can help it.
I need to buy something that will give years of use that can handle some tough work without breaking often. I've checked my local Craigslist but there are no good deals which doesn't surprise me at this time of the year. I'm hoping to find someone in the Portland Oregon area who sells good equipment at a reasonable price.

Need advice on buying a riding mower