Rob
It depends on the person as most will disagree. You have Tucker, Ionics, Omnipole & Concept 20 are the dearer systems. Yhen you have lots of smaller ones Brodex, Stream, Gardiners, Facelift, Outreach, Andrews & many more. You also have suppliers for self build.
I personally prefer Tucker, my system is 4 1/2 years old, never broke down, does everything it says on the tin. The poles & brushs are in my opinion the best, but others will disagree, my work is all commercial & at least 3 month frequency, used by employees aswell. I have tried & got other poles, but overall i would go to Tucker up to 35 - 45 feet, above this we use ergo lite poles, which are realy expensive double the price of Tucker & the new ergo 2 is treble.
I also have a Stream system in a van, half the price of Tucker, but delivers the water the same, i can recommend these aslo, as it does exactly what i want it to do & the people at Stream are realy helpful & try to taylor the system to your needs with no hard sell.
Probably a lot in here have the same dealings with who they have chose, so its personall preference.
Gary