Cub, Deere, Kubota, Simplicity, Honda, Gravely
Think about your mowing needs and style, side discharge versus rear discharge (often the rear ones work better for mowing large outer areas when you mow less often and let it get taller)
No need to get caught up in the big horsepower race, 20 years ago the average lawn tractor was a single cyl 8hp or so spinning a dual blade deck and they did just fine. If you run equip from a PTO, yeah, bump up to HP in the teens, but if just cutting, you don't HAVE to get HP in the teens.
If you have a relatively flat area, with lots of trees and obstacles to deal with, consider the zero turn styles.
