I had the La Spaziale Vivaldi II for about 10 years, so the Mini might be great for you since it sounds like under-cabinet setup.
However, if you can get a 1/4" water line from a 5 gallon bottle/FlowJet pump to your countertop, the Vivaldi II would be awesome (but I realize the bottle/pump/waterline may not be possible).
The Vivaldi will steam great, and is temp stable for nice shots. Its wider than others, and the plastic panels look a bit different. But I really liked it. Decided I wanted to try an E61 so got an ECM Synchronika, but would have been happy keeping the Vivaldi.
Clive sells all the models you are considering. Suggest giving them a call. They are very helpful (and who purchased my ECM from).

I just went through this same dilemma cross shopping the exact same machines, and ended up ordering the Profitec GO.

I really wanted to go with the La Spaz, more specifically the Lucca A53 Mini, but I found something that became an absolute deal breaker for me. The drip tray is plastic with structural grooves and would inherently be kinda a pain to clean. It reminded me a lot of the drip tray on my Breville Barista Pro, and that was a major pain point for me.

The user experience is something I've learned is a high priority for me (ex: warm-up times on my Office Lever not pairing well with me hitting the snooze button too many times), and I think that as a 9/10 times espresso only drinker that the GO seems to be a great contender in the user experience vs. the competition.

I'm swaying towards the Profitec GO. The LS is tempting, but I'd have to retire my lever machine for space. The 300 is appealing as DB and is compact, but no boiler gauge and I have to move it out to fill (and it's heavier than the GO). I don't do milk drinks much to need to monitor steam pressure. Maybe I'm overthinking things?

How is the GO for a couple of cappuccinos here and there?

How are the plastic sides of the Vivaldi? Look ok? The Profitec GO is out of stock which just gives me more time to ruminate here...

Had the spazalie vivaldi for years, great machine, lots of fun but the 53 mm portafilter does limit you a bit on tampers etc, never had a problem cleaning the drip tray

I have had the La Spaz for over 10 years - very solid machine. I has full commercial certification, hence the good quality I guess. The plastic is very sturdy and perhaps less prone to dings or scratches than steel. I customized mine over the years:

• insulated both boilers, even path above the group head

• implemented auto tank refill via google voice command or app (I pull the tank once every couple of months for clean up)

• remote or timer on/off via google voice command or app

Accessories for the 53mm head are less readily available, I suppose it depends on how many you need and how often you change these. I have been waiting for a killer new update from La Spaz but it is not happening

The new Mini Vivaldis are only 15 amp so the boilers can only run one at a time? Anyone see any issues with that? Seems odd to have a double boiler that doesn't run each simultaneously. Ironically even though they modified to run only in 15 amp mode they still need a 20 amp to 15 amp converter...not elegant. I'm swaying back to this machine. May have to sell my lever...

Spaz drip tray cleaning was never an issue for me either. And the tray holds a lot more than my ECM Sync.
53mm bottomless porta filters are available, as are tampers, calibrated tampers, dosing cups/funnels.
Spaz looks different, but not bad. I enjoyed looking at mine every morning.
15 amp is plenty for home use - it will be waiting for you, not you waiting for it.
Yes, one boiler at a time - brew has priority, but it heats up fast after pulling a shot.

Anyone try the Dream T buttons and have any opinions? Vs Vivaldi?

Thoughts of Mini Vivaldi/Dream T or the Profitec Pro 800 (if I can fit under cabinets). Anyone with experience with these? Comparing temperature control, shot quality? Buttons feel ok on the Dream? I like the simplicity of the lever...having a manual one now and appreciating ease of maintenance.