I went through this exact scenario 2 winters ago. At the end of the previous summer, my '89 Wheel Horse 520h broke a rod. I spent the winter doing the same kind of research you are talking about here.
I mow about 1.25 acres at my house and had the opportunity to pick up a mowing job that's closer to 2 acres. Both lawns requiring some maneuverability and significant hills and steeper slops mowing. The mowing job was previously mowed by someone with one of those cub cadet zero turns. They are very nice machines and do a great job on hills but this job is steep enough that they still could not handle it.
For years I owned old garden tractors (JD 318, Wheel Horse 520h, Cub Cadet 1450). I want to work on old stuff for fun, not because I needed it to mow the yard. I refuse to waste my time and money with big box store junk. This led me to the conclusion that I need a 4x4 subcompact. The ability to add a FEL, 3pt and rear PTO are all added bonuses that make the monetary investment more worth it.
In shopping, I came to the same conclusion you did... PRICE! Used was my only affordable option. You obviously never know what you get buying used so I at minimum wanted to buy from a reparable dealer in the area that other people spoke highly of. I spent some time, as you are, figuring out which machine would be the best machine to buy used. I read a lot of reviews and read a lot on people's opinions on forums.
It led me to the Massey GC series (made by Iseki). For similar age machines and similar hours, they ran about $2000 less then Kubota or Joh Deere. Most found them to be comparable, if not better in some ways, but at a better price. I found a 2012 gc2400 with good hours, an MMM and FEL hook ups (did not have the loader) at a dealer 45 minutes away.
I have been very happy with the machine. It does not have loaded tires, but I am constantly impressed with how well it climbs and how stable it is with R4 industrial tires. Different tires would probably perform even better but they do not tear up my yard. if you are used to a general compact tractor, it will feel twice as fast. Not a zero turn, but with a knob on the wheel, it took 45 minutes off of my mowing that took 2 hours with my old wheel horse. As long as its not to wet, it also drags logs out of the woods for firewood that I did not think it would be capable of.
If you want something that will mow faster then what you have had, is built better then what you have had, will mow hills better then what you have had, can do more then what you have had and won't break the bank, a used subcompact tractor is exactly what you need. I just so happen to like the Massey and highly recommend it.