I have 20+ acres of hilly, rocky, mostly wooded land. I am by no means a tractor expert, only had two.
The first was a Massey Ferguson 65, 4 cyl Perkins diesel with a loader, 2x4,2 range, 6 forward gears. It had plenty of hp, but there was rarely a gear slow enough for the work I needed to do. I was constantly getting stuck with a full bucket.
My current tractor is a Yanmar 276D, powershift, loader, 4 range, 12 forward gears, 4x4, 27 engine hp. Traction is vastly improved, and I can find a suitable gear.
I think 4x4 and gearing are as important as hp. Most times my little Yanmar does way more work than the more powerful, heavier MF.