And don't forget about the Altec Dave, or HydraMaster.
There are very few of us who have day in and day out experiences of more than one of these newer top spec machines, so you tend to have a lot of biased opinion.
So, which is best? IMO all of them! My procedures allow me to work with cold water within my own marketplace and my Scorpion XPS works really, really well for me.
One of the benefits for all of these high end machines is longer hose runs. Mine is excellent upto 100', good at 125' and acceptable @150'. These figures are for use with in-van auxilliary tanks. If you use the machine as a porty, you can add about an extra 50ft to these figures.
Now the bug thing for many is the heat issue. I'm am not a great fan of hot water going though the pump as it can considerably affect durability, so an in-line heater is the way to go. You then have a choice, either on-board or portable. With longer hose runs, heat will be lost between heater and wand. Less of an issue with a TM because of "heat to spare". So it makes sense to position a heater as close to the wand as possible. 25' seems to be the universal acceptance.
The Scorpion is the lightest weight by quite a bit.
I couldn't give a monkey about looks. Designed by an Engineer or by a Designer? I know which I prefer.
All of the suppliers seem to have a good reputation for support/service. I've certainly found that with mine.
So which machine? Everything else being equal, I think you'll be happy with any of the machines as long as the COMPLETE PACKAGE is within your budget. Draw up a list of your choices, look at the geography and decide whether a nearer supplier will be to your advantage.
A brief story. A colleague bought a Scorpion. He likes heat so later bought an Alltec. Same spec, same components as my Scorp. He worked with me for a day. Remember that my aux. tanks are like adding an extra 50ft of vac hose. He commented that my Scorp "out sucked" his Alltec. Always remember that a typical new machine with new vac motors will always perform one with older vacs. It's called wear and tear, so it's unwise to compare a brand new machine with your older tired piece of kit.
Safe and happy cleaning
The Ken
PS if you intend to do small scale hard floors at sometime, it may be wise to look at a 1200psi machine