You need to evaluate your needs for the tractor. What do you intend to use it for? What do you envision it's capabilities to be?
Personally, my opinion is to go no less than 40 hp, and 4000 lbs. Adding weight is fine, but adding hp is problematic once bought. You don't want to end up like a banty rooster, just scratching around on top of the ground without getting anything done. But, not all situations require the same tractor. What do you want to do with it?
I want to drag some brush and clear out the final 500 feet of overgrown fence line. Move dirt and compost. Move some logs and medium sized rocks. Pull a trailer through my field with rocks, logs, or gravel loaded. Pull my ZTR out of the mud by the pond when needed. I don't have enough to mow to justify a belly mower, with the mowers I already have. I might get a 4 ft brush hog eventually. I have access to a box blade and roller if needed. I don't want to have to buy a bigger trailer if transport is needed. Tractor tires? Industrial or Turf? I might haul stuff in the yard, or roll the yard, so thinking turf.
