Other than electric/air stuff, the toolset that I used most is the 180 degree swivel head ratchet wrenches. They make pretty large sizes now.
The big hardware I've used most were the horizontal bandsaw (get something with a good, finely tuneable hydraulic drop and reliable lubrication system so you can set it and walk away), vertical bandsaw, abrasive saw, drill press, blasting cabinet (the kind that's like an enormous clothes dryer--shut the door, set the timer and walk away), and Bridgeport (good luck with those last two). Somebody else was doing the bending and welding, or else those (bender, welder) would be at the top of the list since you can always use small power tools to cut material if you're lacking $ or space.
Power tools it's always the 4.5" grinder that I use most, then the air grinder, followed by the sawzall and the air body saw. A great tool is a low profile 90* air drill...with a single flute cutter you can put a hole just about anywhere, the head is only about 1.5" thick or something, including the bit.
Mini grease guns, like the Mac Tools kind Budd was selling for a while, are great...carrying case with space for two spare tubes and everything. They fit anywhere and that Green Grease really is great stuff.
For little stuff...a guy can never have too many magnetic welding angles, bottle openers, c-clamps, vise grips, air tools or beer fridges.