Must have:

Kawasaki engine
Heavy fabricated deck
1" spindles
ZT3100 or larger drives
Very large rear tires
Seat adjustable for your weight

I bought an eXmark Radius X series with a 52" deck last year that I'm very pleased with so far. It has all of the features I listed above. There are a number of others out there that I seriously considered and I think I would have probably been just as happy with, but that's what I got. No issues so far. And it came with a 4 year 1,000 hour warranty.

I looked at Kubota, Gravely, eXmark, Scag, and Hustler. I'm sure any of those would have been good mowers. I was originally leaning towards a Kubota diesel but decided I had better get back to earth because I haven't even bought a lottery ticket and don't have any rich aunts.