I've got 40 acres and have about as demanding of tasks as most anyone with similar property. My
B7800 has managed to do a LOT. I've run it for over 1,000 hours now. HST whine? Well, OK. Still gets the job done. Ballast in the wheels and I'm able to make it grunt to the max.
For what my
B7800 cannot do I RENT the equipment. Mostly this has been for digging; backhoes work, but they can't touch the efficacy of an excavator. The astute reader will note that I just bought a Kioti NX5510HC; yes, I am rapidly increasing the size of my pastures and as such I need to have something that will be able to wheel around larger mowers: I am also ratcheting up my clearing activities- again, the
B7800 is able to do just about everything (though I wanted more lift for heavier stuff), but since I'm getting older I need to pick up the pace- I need to get stuff done more quickly.
Keep in mind that tractors are, for the most parts, means of driving hydraulics and running attachments/tools. A bigger tractor w/o the attachments/tools is perhaps worse than a too-small tractor w/attachments-tools.
After my rotary brush cutter I'd have to say that the most effective add-ons to my tractor have been my bucket tooth bar ([obviously, my tractor came with an FEL] the tooth bar allows me to dig, snag and rip stuff) and getting ballast in the rear tires. My box blade then comes in as being the next best tool: I've ripped some pretty big roots with it- yes, chipping SLOWLY away, but it's done it- the unit is indestructible). Have a root rake, grading blade, sub soiler/middle-buster plow and 3pt pallet forks; all but the pallet forks have been used very infrequently.
A LOT depends on your timeframe. If you are in a hurry then rent the most efficient equipment (or hire out the job). Focus spending money on those things that will be higher-frequency on-going tasks.