Electrolux Aerus upright design
I've been saying for a long time that I recommended Electrolux Epic uprights to people looking for a versatile vacuum. Again, it needed more suction, but eve as it was, it was a very good cleaner. As the bag filled, the power dropped noticeably, but even then it cleaned well. That problem is fixed now.
The reason I like the Electrolux upright design is that it's great with tools. Tools-on-board machines are undermined in the usefulness by the collapsible hoses, as Bimmer740 pointed out. They're terrible except for putting the machine at the bottom of a staircase and cleaning as far up the stairs as the hose will reach. Will the Aerus Lux, you've always gotten a full set of TOL hose and attachments, including the Sidekick, so you can use the upright as a canister on hard floors just by putting the matching floor attachment on the wands (full length wands) and vauuming normally. (I've never been much for just turning off brush rolls on power nozzles or uprights and cleaning just with air and no brush bristles touching the floor.)
Also, the Lux machines were in the filtration business before others even considered high filtration as an important performance metric. The cheaper Lux bags filtered to one micron. So did the after filters. The IOTA bags were better than that when they made them (and I'm still upset they stopped), but the newest bags supposedly filter as well as the IOTA bags did. The base machines have micron after filters, and the Guardians have sealed HEPA filters.
I worry some that the Aerus Lux company might not make it, but, if they don't, it won't be because their upright isn't a fantastic cleaner. My single piece of advice for Lux is to lengthen the plastic wands and improve on the quality of the plastic wands and power nozzle necks on the canisters. The upright uses the classic wands and tools, so it's not an issue with this machine.
I recommend the Guardian upright. It's a solid, effective iteration of a very effective design with effective improvements over its predecessors.