I'm going a slightly different route here. This is one area where HP isn't a big deal. If the others are referring to the general size that is associated with a 50hp tractor, maybe, but you could do all of the above with 25hp... just a little slower.
Dad is on about year 5 of his New Holland Boomer, 40+ hp, pretty big.
I'm also going to disagree politely with ShawnG. When it gets too old for a farmer (who uses it twice a day every day), it's perfect for you. Farmers upgrade typically because of features, safety, or they need something bigger, but on Dad's farm we have 13 tractors ranging from a 2015 (the boomer) all the way back to 1932. All of them work and are fully functional with thousands (and I mean THOUSANDS) of hours. The Boomer he has replaced a 1958 Ford 901 Powermaster diesel. The only reason he replaced it was because he's getting old, and the hydrostat, ROPS, harness, and all the safety equipment on the newer rig. Both were 40 hp and would do equal work. The 8' brushog goes behind a 1947 John Deere G making 30hp. The tractor itself looks like a pile of crap, but it never fails to run, and run well.
But to say that old is bad is just not really the case. Most of the big name brand stuff will outlive you twice and never even burn oil. We have a Ford 8N that mows about 100 acres 3-4 times a year, and hauls the firewood trailer all winter. It is really hard to "wear out" a tractor. Starting in the mid-80s, many of the big names (JD, International, New Holland) started switching over to becoming assemblers - meaning they built much of the tractor and increasingly started outsourcing engines, transmissions, drive components, hydraulics, etc. There was a short period for each manufacturer that had a few growing pains, but they've mostly sorted it out.
Much like old cars, old tractors don't really die. Don't get me wrong, I'm glad the old man has a safe tractor, but I'm also annoyed by the nannies... any of which could go wrong leaving you stranded in the field. If you're looking in the new-ish realm, Mahindra and Kubota top my list. If you're looking for something used in the 80s/90s, JD and Ford made some reliable stuff in the sizes you're looking at. Prior to that, take your pick... if you're willing to give up some amenities.
I might consider something like a Ford 2120, JD 2040, or IH 533. Those are 70s/80s models that have proven to be bulletproof, common, new and used impliments are available.