Hello from Wisconsin!
My Mom's family were farmers and one of her Uncles collected tractors. Here's some of what he taught me from an old tractor user standpoint:
Agreed with @Greg Greg's statement; live PTO is a must for many attachments. Hydraulics is very useful. Beyond that, think of the things you may want to do with your tractor.
Cutting basic grass with a mower?
Cutting woody weeds or saplings with a brush hog?
Snow plowing with a plow?
Snow blowing with a snow blower?
A scoop with a hydraulic bucket or a backhoe type attachment?
Pulling a trailer? (Not speaking to a MH)
Grading a gravel road with a grader?
Moving a dumpster?
Hooking it to an emergency generator if the power is out?
Moving downed trees after a storm?
Also important is how you connect these attachments. A "three point hitch" is probably the most helpful because it's an industry standard.
Your land will dictate tire type. Do you need an aggressive tread pattern for additional traction? The ability to put on snow chains? Or will a simple tire do fine?
Do you need a 4x4 or will rear-wheel-drive-only do fine?
Do you need an enclosed cab due to weather?
There are gas, diesel, and LP tractors out there. Does any make specific sense for you given your area or needs? Also consider whether parts are available for an older tractor with a diesel or LP engine.
@KurtKelley speaks the truth about theft. Most states don't license tractors. Not all tractors have a VIN or other identification number, especially the older ones. Find a way to secure your tractor. And while it's easy to do something like yank a spark plug or wires, never forget a group of people can usually push one onto a low trailer and speed away into the night. A friend uses a combination of disconnecting some wires, running a chain from the axle to a steel eye bolt sunk into concrete, and a clamp/boot style lock on one of the tires.
A few words about old tractors:
They are usually easier to repair because they aren't computerized. The only electric is from the battery. Some, like the Ford 8N, are an inexpensive simple workhorse with abundant parts. Just remember that "abundant parts" portion. Others have much rarer parts. You may be out of commission on a parts hunt or will be forced to fabricate your own.
These tractors were made before "orthopedics" was a thing. Those old steel seats welded onto a spring look classic in photos but can be hell on your back after any amount of time. You may want to swap out the original seat for something more user-friendly.
Old tractors were made before OSHA and safety regs were a thing. While this is a pretty hands-on / no-fear group, you really need to remember that they "don't make 'em like that anymore" for a reason. Tricycle tractors (two big tires in rear, one or two small narrow ones in the middle in front) EASILY tip on hills or when making some turns. There are plenty of old timers in farm country who can talk of when Uncle Buck or their Cousin Homer got crushed and killed by a flipped tractor. Wide front (also called "row crop") tractors have larger tires in the front that are farther apart, often matching the rear tire placement. The row crop design is INFINITELY more stable. Watch how you drive on slopes of any type- even a row crop can flip if you're driving lengthwise on a slope or trying to drive up too steep of a slope. These are NOT ATVs/quads and shouldn't be treated as such!
Also, if you're trying to pull a stump or pull anything else and your front end starts rising at all, STOP WHAT YOU'RE DOING. SLOWLY BACK UP TO GET THAT FRONT BACK ON THE GROUND. My own family can talk of a Great Uncle who was crushed when he tried pulling something too heavy and the tractor reared up and flipped down onto him.
Newer tractors are much safer and have less risk than the old classics. Just remember that they're not foolproof.
If you're going to have a manager or groundskeeper use the tractor, I strongly advise getting them trained and going with a tractor that has more safety features than fewer.
Beyond that, Google is your friend. I find that old Fords, Farmall, and John Deere have the most parts and knowledge still out there. You may run into parts and know-how problems with lesser known brands.