Just got off the river and used REO for boats, food, groover and shuttle; Only comparison was a trip few years ago with complete package from PRO.
REO folks were great to deal with, flexible, did some unplanned trailer repair for us, their box a day meal planning worked well for us except their was too much of it. You can always find stuff to quibble with but boats were solid, rigging turned out to be imperfect so you need to be responsible for your own boat, straps were really worn but everything worked and did what it was supposed to...
PRO rents SOTARS which I would have preferred over the NRS boats you get elsewhere but that's more perception than based on anything factual. AT the time the PRO equipment we got was in a bit better shape than what we got with REO but not to any meaningful degree.
Without the benefit of a comprehensive head to head comparison I suspect all the established companies will do what you need them to do; you can find good stories about all, as well as a few complaints; might depend on whether you care which brand of raft you get and the approach to meal planning and organization