If I was forced to go back to a tractor style mower from my ZTR I would look for a good used Simplicity or a new non box store Husqvarna. Simplicity was known for making some of the best lawn tractors, cut quality is top notch and they were built well. Husqvarna offers a lawn tractor with the good Kawasaki FR series engines and fabricated mower decks. I had a JD 110 lawn tractor for years and it was ok but I wouldn't touch a new JD with a ten foot pole.
Ding, ding, ding. This! Absolutely! I tell this to people all the time when they say, "I own a Husqvarna, and it's a POS, so therefore Husqvarna makes chitty lawnmowers." Or, "my JD is a POS, so therefore all JD mowers are POS." Some guy was telling me that Husqvarna mowers are POS, and to get Craftsman. I'm thinking, "hey dumb arse, they're the exact same mowers with different paint, decals, and hoods. I know this because I was a tool maker at Husqvarna Outdoor Products in Orangeburg, SC for several years. Over the years they've had several different names. (Roper, Frigidaire, AYP, Electrolux, etc) Pre-China Virus they were the largest manufacturer of mowers in the U.S., if not the world, even though I've heard that post China Virus they went through some pretty large restructuring, but back in the day we had probably 30 different brands we made mowers for like Craftsman, Dixon, Ariens, Weed Eater, Poulan, Poulan Pro, McCulloch (brands I thought just made chainsaws) Murray, etc, etc. I can tell you that Husqvarna absolutely makes a crappy mower, but they also make extremely good mowers. Same with JD. Those mowers that Lowes and HD sell may look the same, but they're not the same as what's sold at a Deere dealership, or a lawnmower dealership that specializes selling highend outdoor products. Do you feel that a Rancher or Farm Boss is going to be as good as a Husqvarna or Stihl professional saw? Walmart has some nice looking TV's, and they maybe good enough for you, but do you think it's going to be on the level as a $6K-$10K TV at Best Buy just because they're both Samsungs? Are you going to shop Lowes or HD for welders to start a welding business, or are you going to buy your welders from a welding supply business that you want to form a relationship with? You can buy a decent home welder at somewhere like Northern, and even Harbor Freight welders work pretty decent for a hobbyist, but are you going to go there to buy a $60K industrial diesel engine driven welder, like a Miller Big Blue or Lincoln Air Vantage, especially when service may be needed for warranty work, and you need to buy gas, and rods, wire, parts, etc? So why would you go to a large retail store that sells a lot of things, but specializes in nothing for a great mower? Yes the Ariens APEX that you can buy at Lowes is a good mower, but Lowes can't perform warranty work on it, and that same mower can be found at dealerships that can perform that for you, even if it costs a couple hundred more the lawnmower dealership is the better overall route.
Basically Husqvarna makes mowers rated for as low as 800 hour, but they also make mowers rated up to 3,500+ hours. Same with other companies. If you go look at, and sit on the display mowers at Lowes/HD, and then at the dealerships, the dealerships mowers just feel better, tighter, beefier, heavier, etc. There is a difference on what large retailers order, and what outdoor product dealerships order from the manufacturers. Maybe 1 or 2 of the large retailer's more expensive models are more entry level, industrial grade mowers, (Ariens APEX for example) but you've got to know what you're looking at.
There are quite a few good brands. Also generally speaking the better zero turns are better build, more commercial grade than your tractor mowers, but most manufacturers make cheap entry level ZTR's as well. (Husqvarna RZ for example) I really like Exmark ZTR's. I also like the older Husqvarna MZ's and they're a great value, and have been around for about 2 decades so they're well made, but without a lot of the modern fluff that will likely become a reliability issue at some point. But all your highend brands will have good machines. I think Toro gives you a lot of bang for your buck, even if they're not the most commercial brand, plus they bought Exmark in 1997. Obviously the commercial JD is very good, as is Cub Cadet. Kubota wasn't making wave in the mower business when I was machining for the engineers at Husqvarna so we didn't study them that I can remember, but they've come up it seems. I looked at them last summer, and thought they were very nice. Ferris is very good, and Stihl has bought them, or bought into them, or something as they've got the same chassis/suspension from what I was told. Ariens/Gravely are good, but I always felt cramped on them. I still wish they made Dixon mowers. I always like the Dixon mowers we built. At their core they were the same as a Husqvarna mower, but that's like saying at it's core an Escalade is a Tahoe. Yes, but it's an extremely well fitted Tahoe. Those MZ/PZ based Dixon ZTR's had some awesome seats.
Lastly I prefer Kohler or Kawasaki engines Both are excellent. Briggs & Stratton Vanguard is highly touted by some people, but I don't know as much about them. I'm sure they're GTG though, but Kohler and Kawasaki seem more popular in this millennium. Exmark actually makes their own engines now, so does Toro use Exmark engines, since they own Exmark?