I've gotten some pretty good stuff at HF and I've gotten some real junk. I'm leery about their hand tools. It's been my observation that, other than the occasional "factory reconditioned" power tool, all the brands, "Chicago Electric", "Chicago Pneumatic", "Pittsburg", etc. are their own house brands for Chinese (?) imports and the quality is very "hit or miss".
My policy for buying tools, both power and hand, is to only cry once. Pay the price for good quality tools that you won't have to replace when they break the first time you hit a tough job. It's very annoying to interrupt a task for a trip to the hardware store to replace a split socket.
You probably don't need the most expensive, top line, professional grade, but they are nice to use. Just don't drop too far down the quality ladder. I always leaned toward the Sears Craftsman line for wrenches. But that was many years ago and I can't comment on what the quality of their hand tools might be today.
I'll admit that I've little experience twisting wrenches specifically on a tractor, but I am getting a little now. I'd guess that it's likely that a 1/2 drive will handle a large majority of what you need to do. Heck, even a 3/8 drive may handle a big chunk of it. But unless you're going to be doing some real heavy disassembly work, I'll vote with your neighbor. I think a 3/4 drive is overkill; an unnecessary expense, too big and bulky for much of what you'll be doing, and will encourage you to overtorque the smaller fasteners. You'll know what I mean the first time you snap the head off a 10 or 12 mm bolt using that huge ratchet. For the BIG stuff, I'd go with a few open end, box end or combination wrenches in the sizes you need.
These are just my personal prejudices. If contradicted by someone who has spent years up to his/her elbows in tractor guts, don't hesitate to ignore what I've said.
