As long as you don't get some cheapie thing from Harbor Freight, they're all about the same. They're tighter when they're new and loosen up a bit as they age - a lot depends on how they've lived their life (being wheeled around roughly, etc). Any marine store will have something that will work. All of them "wheel" about the same, too.
Fulton makes an aluminum body jack that is tighter (doesn't wobble as much) and wheels nicely. I think it's called the F2, or something like that. But honestly, it's kinda overkill ($$) for a small boat when a $40 jack will do the job very well.