There seems to be so many different frame sizes and HP ratings in the 20-30HP tractor range it is hard to sort value from noise.
The most efficient way to shop for tractors is to define potential tractor applications first, then determine bare tractor weight necessary to safely accomplish your tasks. Your primary tractor task is pasture mowing.
The fundamental importance of TRACTOR WEIGHT eludes many tractor shoppers. Heavier tractor weight is more important for most tractor applications than increased tractor horsepower. Bare tractor weight is a tractor specification easily found in sales brochures and web sites, readily comparable across tractor brands and tractor models, new and used.
Shop your weight range within tractor brands. Budget will eliminate some choices. Collect a dealer brochure for each tractor model in your weight range. I spreadsheet tractor and implement specs, often a revealing exercise. I have a column for cost per pound.
Selling a used tractor is easy. Selling multiple light implements in order to buy heavier, wider implements for a heavier tractor requires a lot of time. Depreciation on implements is generally greater than depreciation on a tractor.
Heavier tractors are constructed with a longer wheelbase and are built using thicker steel to withstand greater stress. Heavier tractors are more stable under load. Heavier tractors have larger wheels/tires. Heavier tractors with large diameter wheels/tires have more tractive power pulling ground contact implements, pushing a loader bucket into dirt and pushing snow. Large wheels and tires increase ground clearance, enabling a heavier tractor to bridge holes, ruts and tree debris with less bucking and less operator disturbance.
Very generally, subcompact tractor have 7" to 9" ground clearance and a bare tractor weight of 1,300 to 1,500 pounds.
Small compact tractors, exemplified by the Kubota 'B' series, have 12"+ ground clearance and a bare tractor weight of 1,600 to 2,500 pounds.
Within subcompact and compact tractor categories, a significant tractor capability increase requires a bare tractor weight increase of 50%. It takes a 100% increase in bare tractor weight to elicit MY-OH-MY!
Most tractors under 3,000 pounds bare weight operate in residential or hobby farm applications on one to ten flat acres.
For mowing, horsepower should be your second consideration. Every increment of increased mower width requires an increase in tractor horsepower. A 26-horsepower Kubota 'B' will operate a 60" pasture Rotary Cutter cutting a full width swathe in pasture grass to 30" tall.
VIDEOS (4):
Kubota BX Series VS. B Series - YouTube
Kubota B261 VS Kubota B265 - YouTube
Comparing Finish Mowers (midmount VS 3-point) - Kubota B261 - YouTube
Brush mower features with the Land Pride RCR1872 - YouTube