I got a Kubota MX5100 (51HP) to take care of our 22 acres.
The most important criteria when making my decision was that the tractor be fully mechanical. If something breaks, I can work out what's wrong and fix it. In an electronic tractor if some random 5¢ diode goes, your tractor is an expensive doorstop until some specialist with a magical diagnostics box comes out to isolate the $x00 or $x000 module that needs to be replaced, and replaces it. Most competent folks can troubleshoot and fix mechanical problems. The same cannot be said of electronic problems.
Our property is not a farm and we don't have large areas that need the usual types of attention (tilling, seeding, spraying, harvesting, etc.) that farmers need to give their fields. The chosen tractor, therefore, needed to be an all-rounder. Not so small/light that it couldn't pull a 6–700kg round bale or pallet off the back of a truck, but at the same time not so large that it can't manoeuvre between trees, or so heavy that it ruts up the yard. The MX series is the cross-over range in Kubota's line-up between "proper" farm utility tractors and compact tractors, so was a good fit for our needs.
Speaking of rutting up the yard... Put R1 Agricultural tyres on your tractor and you can pretty-much kiss your lawn goodbye. The tread is so aggressive that lawn doesn't stand a chance under most conditions. The R4 Industrial tyres don't have as aggressive a tread pattern, and have stronger side-walls, so whilst they don't provide as good traction (especially on clay), they do last longer, are more puncture-resistant (handy for those of us with woodlots), are more stable when doing loader work, and don't outright destroy your lawn. R4 Industrials are the "all-rounder" tyre.
All that said and done, through, a tractor is just a mobile power plant. It's what you connect to it that makes it useful.
On the back end you want a PTO and a proper Category 1 (or 2) three-point hitch. Cat 1 opens up a world of possibilities. Be wary of sub-compacts with Category 0 or 'limited' Category 1 hitches. Category 2 is a luxury that comes in really handy if you need to hitch bigger/heavier implements (or other loads).
Hanging a counterweight off the three-point is the best way to reduce the load on the front axle that you will experience doing loader work. It is about the only time that the placement of the mass matters. When doing anything else what you want is more traction, and wheel-weights or ballast work absolutely fine for that (as well as freeing up the three-point for something else). Unless you are in a place that experiences severe/prolonged frosts, put standard tap water in your tyres and the rims will be fine for a quarter-century or so. You won't care about bleeding/empting them because the water only costs a buck or two, instead of a few hundred bucks as is the case with more exotic fluids (e.g. CaCl, beet juice). The rear axle of a tractor is incredibly strong — you're not going to wear it down or break it by adding weight there.
Disclaimer: Weighing down the rear wheels can give you a surprising amount of extra traction. In the vast majority of cases this is a "good thing" in the same way that a sharp knife is a "good thing". In certain edge cases, however, things can get 'exciting'. If you don't mind a bit of 'excitement' in your life, go right ahead. ;)
It should go without saying that any time you add anything to increase the weight of a tractor, the amount of rutting you will cause increases. Shifting into 2WD and driving straight as an arrow can only help so much.
On the front end you should have a loader with a universal skid-steer quick-attach (SSQA) system. Well, it's "universal" in that everyone in the universe — except for John Deere — uses it. Buy into the JD ecosystem, however, and you're stuck with a much more limited range of proprietary (and nearly always more expensive) loader attachments... forever.
With a SSQA the world is your oyster as far as what you connect to it, and connecting stuff is a breeze. Buckets, 4-in-1s, grapples, forks, you name it.
Based on the thousands of buckets of soil that I've excavated from the pond area so far, 4-in-1 buckets are fine as long as you're digging mainly sand (or slightly gravely/clayey sand). The going gets tough when encountering cemented gravel or heavy clay. A dedicated bucket with a tooth bar would help in the former case, an excavator in the latter. I have a 500kg counterweight and it's not enough — the MX5100 breaks traction on a regular basis. Most of Kubota's tractors (probably all modern tractors) are in the same boat: They have a very high power-to-weight ratio. You really need mass on the back end to harness it all.
4WD is mandatory for any serious loader work, and highly recommended otherwise. Unless you're doing field work (which includes mowing) all day long, 2WD just won't cut it.
A hydrostatic transmission is pretty-much mandatory for loader work, optional for most everything else, undesirable for field work, but really easy to learn and use.
Then there's the backhoe question. Over the next few weeks I'll be laying a few hundred metres of fibre-optic cable and 50mm water line for irrigation and bushfire defence. I predict that will constitute about a third to a half of all of the "trenching" that I'll ever need to do on this property. It will cost me ~AU$200 to hire the trencher for a weekend and get it all done. A new backhoe costs ~$12,000. One should really think long and hard before buying a backhoe. You can rent an awful lot of specialised equipment (e.g. trencher, excavator) for the same amount of money.
Finally, and perhaps more philosophically, one should remember that a tractor was designed from the outset to PULL things behind. It was not designed to PUSH or LIFT things in front. If you think that most/all of your work will be done in front of you, then perhaps a tractor isn't the right tool for the job? Excavators and Skidsteers are both remarkably capable and versatile machines that let you focus forwards. Food for thought.