Of all the suppliers I've used, I rate Solutions and Restormate on a level 1st place in terms of service. "Big enough to cope, small enough to care" is a well used motto but totally true. Solutions have carved a niche by bringing out their own exclusive range of products, some of which are fantastic, the rest are simply very good.
Hydramaster I've only really used for bits and bobs, as I don't have one of their truckmounts.. I'd say they get the job done well but recently took about 5 weeks to repair my RX-20 and get it back to me! But disregarding that, the service on the whole I've found good.
Woodbridge stock a vast array of bits n bobs, pump parts and components etc but delivery can take ages and the service sometimes hit & miss
Alltec installed my TM and it really is a game of two halves with them. In an emergency they've got me back up and running very quickly but for other more routine stuff they have been abysmal. Just a couple of examples: My TM's chemical jug was missing when I got the machine, and 18 months later I've given up asking for it to be supplied. I snapped the crank handle off my solution hose reel about a year ago and asked for a replacement... nothing happened. Stuff like that isn't major but when little things keep annoying you like that it leaves a sour taste in your mouth.