I have a B7510 Kubota, 23 hp and am going tractor shopping in the spring for a bigger one.
What I have is perfect for work around my house, tilling the garden and mowing the 3 acres of my land and the neighbors that I keep up as well.
When I start working on the 350 acres I hunt with it, mostly bush hogging with my 4' bush hog, I come up way short.
Kubota makes a B series with 31 hp and an L series that starts at 31hp and goes up to 45hp, lots of models to pick from as you step up in size.
My friends have a mid sized Mahindra tractor that is much sturdier than Kubotas. They are pretty astute shoppers and research everything they buy, this is why the decided on a Mahindra.
One more thing, don't even think of getting a tractor without a front end loader, handiest thing on the face of the planet. On my small tractor the bucket weighs 400 lbs and I have to run in 4wheel drive all the time to push the extra load.