I have a 1960 Farmall 460. I am definitely into old tractors, and collecting old iron can turn into a hobby as much as guns. I have friends with tons of old junk. It's a lot of fun haha.
I've been told to avoid the fords. Stick to IH and John Deere primarily. Old iron isn't trouble free, and will require parts and upkeep, and some old tractors are getting hard to get parts for. Stick to USA made. I'm real tempted to get some of the import tractors, as if you can find a German made john deere, the look attractive, but there is some question on getting parts to keep those going.
I've seen guys pulling a 10' batwing behind a Farmall 560 before, and they say it handles it just fine. Depends on what you're cutting, but Farmall 560 and 460 are about the cheapest HP you will find. Mine is rough, leaks like crazy, and is not comfortable, but it sure is cost effective.
John Deere 3020 is probably what you want though. Especially if you are willing to spend 10-12k. There is one not far from me that is asking $8k for a diesel, and I'm trying to figure out how to scratch together enough money to get it, and restore it.
tl;dr - old tractors are cool and you should buy a bunch of them and post pictures.