My aluminum jack has held up well, but it's not something I'd recommend for trucks/SUVs. It'll lift my Tacoma but it doesn't have nearly enough reach. Which one are you looking at?
I've got a few floor jacks around here. My HF is ok but it tends to stick closed. When enough pressure is used to turn the handle is snaps free and drops the whatever like a hot rock. My Sears never does that, then again, my Sears is older than most AT'ers so YMMV. My favorite for heavy stuff is my Norco, great jack but most tinkerers don't want shop grade stuff.