Mostly personal preferences.
I never actually cleaned with the Kinetic, I held it and the head is so big and heavy that I felt it would not work in tight spaces or curves, be perfect for large flat areas. And more importantly it was heavy and seemed like it would be cumbersome and hard on the wrist which for me is the most important issue. We can all afford the tools but not the permanent damage to wrist, etc. (Again, in all fairness I never actually cleaned with it.)
Like Billy I did not find the SS tool to do a good enough rinsing/flushing job or it needed too many repetitions. It was convenient to hold and had decent maneuverability the ability for continuous flow and no over spray (can't mist). Unlike Billy I had lots of clogging issues with the KleenRite tool + the little brass connector, broke frequently and drove me nuts.
The ProChen tool is very hardy and durable, good valve, didn't like the round knob (bypass) as I felt it could hit/snag fabric or wood, you can mist with it (which is both an advantage or a disadvantage.)
My favorite is the PMF spray in vacuum 4.5" tool. Very maneuverable, can reach anywhere, no over spray, no misting, low price. Valve is not very good (not as bad as some claim) sometime the jet can be an issue, needs to be adjusted well.
I don't do it but I can see working with two tools, one for large flat areas and another for the harder to reach/curved areas.
As I said, best way is to try the different tools. If you do plenty of upholstery it will be time well spent. Finding a tool with which you feel comfortable working that gives you the results you are happy with, will save you time and keep your wrist functioning.