I don't agree with filling the rear tires which seems to be a popular option today. Neither of my M9's have filled tires, never have. I run the optional Kubota cast centers on both, never had issue one with picking up anything within the capabilities of the front end loaders.
The issue with loaded rears is compaction because you have the incorrect tread design. Always R1's bar tread tires for farm work.
If you are running hay or row cropping (which I do), compaction becomes an issue and so does destroying the plants themselves. Why farmers run duals today or tracked machines. Why destroy the crop by compaction. Counter productive.
Far as brand of unit, I run Kubota's because they are reliable tractors and I have a dealer close by. At some point you will always need parts. Running a tractor with no support close y always entails a wait for parts and if it's something that requires professional (dealer) intervention, you are screwed.. I prefer not to be. When I need my units to perform, it's NOW, not waiting for parts.
I also have a feedlot operation (I raise steers for sale and have for years. I cannot remember one time where I 'raised' a cull in the bucket. I just drag them out and deposit them in the containment pit when they die.
Both my M's have substantial front loaders that can handle any round bale I make up to 6 x 4, no issue. In fact, I usually put a rear spear on the 3 point and a spear on the front and run 2 at a time. Never an issue, never has been.
Reason I state at least 50 pto horsepower isn't because of the power but the weight of the units. You need a substantially sized unit to move rounds and move cattle and clean dry lots and they all will require R1 tires and most likely front wheel assist.
I consider a 50 pto horsepower unit the MINIMUM size. Anything under that won't work... and finding a used unit that is is good shape will be difficult. Users are getting wise to the T4 final units and their inherent issues so the used market (pre 4 units) is getting tougher all the time.
I went 600 miles to buy my last M9 and was lucky to find it and it still needed some serious work to bring it back to being a reliable unit, in fact I put almost 6000 bucks in it to get it to a state of reliablilty.
I realize that most of the posts on here are about people buying old tractors, usually small ones and then keeping them running. Not me. I depend on mine for farm use. Not a hobby thing for me. Farming for profit isn't a hobby, it's a vocation.
I don't care what brand a person buys. All distills down to reliability and properly sizing the unit for it's intended use. Too small only causes grief down the road when it won't perform the intended tasks.
For me, anything under 50 horse I consider a toy, hobby unit. I prefer over 75 pto horses. My M's both have 90+ pto horsepower btw and both weigh over 8000 pounds dressed.
If I was the OP, I'd consider a later model unit with front wheel assist, front end loader with SSQA, at least 2 sets of rear remotes and a gear drive transmission, with a hydraulic shuttle and no dry clutch as well as Cat 2 3 point with draft sensing and I'd steer clear of high meter hour used units as well. With a high hour used unit, all you are buying is someone else's issues. People don't sell older units that are issue free, they keep them and use them. When the issues outweigh the usefulness, they then sell them.
My opinion, but then I use mine for farming. Not a hobby.
My cab unit, I bought in 2004, new. It was 52 grand. Runs like a top but it gets maintained on a tight schedule. My open station M9 is a 2002 and I bought it used (600 miles away) and I put around 6 grand in it in hard parts to bring it back to a level of reliability I require for my operation. That 6 grand included new injectors, a pump rebuild, new loader bushings, new tie rod ends, rebuilding the outer left outboard planetary a new front driveshaft coupler and miscellaneous parts, some of it I did myself because I have the tools and the shop but some of it was done at my dealer because I lack the expertise to do it. Both of them get Kubota filters, premium oils and greasing every 10 running hours and both are kept inside when not being used.
Finally, both are appreciating in value as well, a big plus for me as I don't plan on doing this forever.