Toro is underrated. I just have the little residential single cylinder ZTR model and it has been impressive. The keys are air filter type and size, most are too small. This thing is overkill and it's very robust with a metal screen reinforcement both inside and outside and also has a foam pre-filter. Uses an automotive style oil filter along with pumped oil. If you keep the AF cleaned and oil serviced it'll last. Use a synthetic oil rated no newer than API SG. New automotive engine oils are not what air cooled engines need. No ZDDP.
All that said the Kawasaki is a good engine. This video shows some of the differences.
Any of those three will serve you well. I beat the crap out of a cub cadet on two acres of lawn going on 6 years now and I really wish I had gotten a commercial grade mower. It works but it’s getting sketchy. I’ll be happy to get it through any part of 2019
I've got a Ferris 52inch and while it's been a good mower for 3 years I'm a bit disappointed in the suspension. It's not as cushy as I was hoping for. Definitely better than no suspension though.
I didn't step up and pay the extra money for the fully independent front suspension, mine just has the pivoting beam type, but sometimes I wish I had.
Also, the deck seems to clog up more frequently than the tractor style riding mower I had before. I've already had to clean it once this season because it was so clogged up it wasn't cutting good. And I really try not to mow when the grass is wet.
I haven't had any other ZTR's to compare it to.
I have 2 Gravelys, 1 is 66" and 1 is 48" with bagger. The 66" is commercial and I love it, have about 650 hours on it now. The 48" is not commercial grade and is a little iffy at times. What ever you get don't get one with Briggs engine
When we moved to our current place in 2005, the previous owner had just purchased a 50" Cub Cadet. He wasn't taking it with them and offered me a good deal so I bought it. 24hp Koehler still going strong but it started to need some oil added about once a month last summer. Been through several sets of blades, and one deck cable and otherwise no complaints over the last 13 years.
I just bought a Spartan this year. 61” commercial grade with a fuel injected Kohler engine. They are made by the guy that designed the initial bad boy mower and I guess are built on the same street. It’s got a lot of features with the control panel which idiot proofs a lot of stuff. The SRT model I got has several features like independent suspension on the drive wheels, a Parker hydraulic drive pump for each wheel and the seat has a lot of movement to make a smooth ride.
Couldn’t tell you anything about longevity but it’s wide open, simply built and looks easy to work on. I think their RT model is close to your price range and has several of the heavy duty features standard. Just google Spartan of Oklahoma to get their number.