There are literally dozens of tractors from various makes in the 30-50HP range. And they vary in size by ALOT. Anywhere from a 2000lb tractor to 6000lb tractors. 30-50 HP covers 3 frame sizes. SCUT(sub-compact utility tractor), CUT(compact utility tractor), and utility tractor. AND there is a BIG difference.
And I will also ad that for only 5 acres, I would be looking at the SCUT's anc CUT's and NOT the UT's.
What you really need to do is go to some dealers and get a "feel" for the real-world size of these machines. When you do, make note and look at the specs. Then compare brands for similar models.
It also wouldnt hurt to decide on what sized implements (bushhog, mower, blade, etc) you what to be able to handel. Because that can help steer you toward the right tractor.