As previously mentioned quality and type of build are indeed factors, and here's another angle to look at. I am in the hobby of restoring vintage autos and custom fabrications. When I looked into a hoist, I knew 4 post was the safest way to go, and also has portability pending build and manufacturer. However I opted to go with a 2 post lift for my needs. Why? The biggest downfall I saw with the 4 posters, was that they were all ramp style lifts, meaning the suspension & body had to be intact to use the lift and could not be serviced on said lift, it would only be good for repairs such as maintenance service and engine/trans repairs. The 2 post uses the arms and pads which come with several adapters and configurations for any need, allowing you to remove body's from frames on frame vehicles, lifting beds & cabs on pickups, & performing suspension or body work on any vehicle. The 2 posts come in clearfloor (no plate across floor but has beam across top) or floorplate (no beam on top and has ramped beam across floor) designs. I got mine from northern tool, decent price, and went with the 10,000lb clearfloor type, as my shop has an 18' ceiling which matched the height of the lift at the top beam, and I felt that to be a more solid design, especially with a thinner floor concrete thickness. I also went with the wide leg profile to allow more versatility of use for larger vehicles (and the tractor). I further reinforced it on the thinner floor by fabricating an extended H-shape foot design that mounted between hoist feet and floor from heavy wall square stock steel, which gives the feet better stability and holding leverage, so as not to need to chisel up my 4" thick floor and pour thicker footings.
-Chris