having used quite a bit of wet vacs
I might add some pros and cons (only from my own experience, not suitable for anyone else)
All of them are superior to any Dyson or Kirby what comes to "no dust smell"
Rainbow:
D series: Nice and compact, very silent and pleasant sound, although having rust issues on the central hex nut holding the fan blade (I wonder how that is taking it on the long run).
E series: Somewhat better on that, yet a shrieking ramp-up sound caused by this horrible reluctance motor, it makes my molar fillings fly out. I just hate it.
Hyla: Better cleaning performance (even though only slightly better than Rainbow. Sound ok.
Delphin: Highest cleaning performance, sound ok but terribly loud (due to the lack of foaming stuff inside).
DeLonghi: A joke what comes to water filtration vacs. Sound average to ok, filtration is a bubble bath of sludge, there is no circular action in it. The pre-filter is always wet.
Thomas wet/dry and steam vac: A joke. Wet action between average and forgettable, dry suction good but not any better than a standard vac. Steam cleaning plus suction: You are better of with a steam generator iron SANS suction. (Messy, not working, more action to the job than using a good professional mop set).
None of them clean carpets as good as the Kirby does, although Hyla and Delphin come close.
But all of them outdo Kirby and Dyson alike on "overhead jobs", corners, floors.
Workmanship: Best: Delphin
Second: Rainbow and Hyla.
Worst: DeLonghi
None of them will filter non-water-catchable stuff like oily substances or plaster dust. (Thus the back or post "washbasin" filters).
Some manufacturers suggest using scented oils to make an emulsion in the basin to catch the oily stuff (works well until you have to empty out the basin: This idea will make you dishwash it with liquid soap each time, so what is the time saving point here?)
All water based vacuums give me a better air to breathe than any other vac, most of them give me a headache of a daily empty out job, none of them can groom my fitted carpets well enough.
One gives me a grinding jaws movement almost until biting out my molars (Rainbow's E series, I love the design, but the sound gives me the creeps).
Note again: Just my 2 cts, nobody else's. May anybody decide for him/herself.
Buying factor (for me): None of them. Will stick to my Kirby-Nonkirby-selection along with small babies for quick pickups.