
SEBO
AIRBELT E3 Premium
Ultra-durable, 10-year warranty, but expensive with short cord.

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I bought a Dyson V15 from Costco and returned it for many of the same reasons you quote and also because the parts fit was terrible; luckily Costco came through as usual. I bought a Kenmore Elite cordless upright that solves a lot of your issues and comes with 2 batteries. Since it is an upright instead of a stick vacuum the weight is down low, and the canister lifts off for portable cleaning. It is well sealed and all filters can be washed. One battery lasts me for the whole downstairs of a 3000sqft house and I still have another battery ready to go. The model is CU7005. I got it at Walmart for $320.
How about Kenmore Litening cordless upright vacuum cleaner CU7001? Light weight (13 lbs -- a little bit less than the Rewind), adjustable suction, hair detangling (good for dealing with cat hair), brush roll can be turned off, easily removable/replaceable battery. Price is right too.
I just replaced our upright vacuum with the Kenmore Elite Litening cu7005. It is really awesome. If you buy it on Amazon and Kenmore's site, you can order with two batteries. I vacuumed our living room multiple times without recharging, while using on Max power. I swapped to the second battery to do my daughter's room. I have no qualms about replacing our plug-in vac with a cordless one. Definitely more powerful than a typical cordless vacuum.
I know majority HATE Shark but we love our shark stick vac. The duo-clean feature is amazing on hard floors. I bought our Ionflex 200 so many years ago, refurbished, on Amazon. The battery is still excellent and it works great. I also bought a Kenmore Elite Litening 7005 (cordless) to use as our main vacuum, replacing our 15 year old upright.
Kenmore Elite Litening CU7005. Got mine at just over $300 on Amazon with two batteries. It's quiet and the suction is really good; not like a typical cordless vacuum. Plus, if they want to use the hose, you can pull the canister off the upright part and carry it around. I was able to vacuum my living room 3 times on max and my daughter's room with one charge of the first battery. The dock charges the vacuum and the extra battery. Edit: it was $290 total.
I bought the Kenmore Elite Litening and love it. It's light and very powerful. I bought the package on Amazon, with two batteries. Honestly, I don't need the second battery. This was purchased to replace our old upright. https://a.co/d/4BARVnK
I love our cordless Shark Ionflex IC205. It is going on 6 years with original battery. I love the duoclean brushes and it has great suction. We just replaced our 15 year old upright with the Kenmore Litening. It has a 24v battery and I vacuumed my living room on normal and then put it on max to re-vacuum and it only used 30% of the battery. The listing on Amazon comes with two batteries for under $300. Not sure if it's available in Europe but it's worth looking at.
I got a Kenmore Elite Litening. Got it for under $300 on Amazon and it came with an extra battery. Way more powerful than our Shark Ionflex. (which we still love). We got the Kenmore to replace our 15 year old upright that melted the brush roller...
1) The commonly recommended units in that price range are the BU4050 and Kenmore elite upright (great but bulky) 2) IMO yes it’s absolutely worth the premium. The Sebo is a commercial workhorse that you can use in your home. Plus it has a 10yr warranty if you purchase through a local dealer. I’d also look at the dart - some people here prefer it over the Felix.
Older sharks used to be “okay”. New ones are straight up garbage. You’ll be lucky to get 2-3 years out of it. You want something bagged too. Bagged vacuums last much much longer than bagless. And clean and filter better too. If you can swing the extra budget. A Sebo dart is an absolute workhorse. If not, Simplicity allergy or Kenmore Elite upright.
In that price range you've got a few reasonable choices. Kenmore 600 would probably be my top choice. Large capacity easy to get bags, good power nozzle for carpet, mini motorized brush for upholstery, stairs, and the car. Good performance all around. For a strictly carpet vacuuming upright, the Kenmore Elite is pretty good for the money. Very very good carpet performance, decent hard floor vacuuming for an upright, the hose is short though and tools aren't amazing. Large easy to find bags. Either would work I think with the 600 being a more versatile option.
Kenmore 200 for a canister, Kenmore Elite for an upright

SEBO
AIRBELT E3 Premium
Ultra-durable, 10-year warranty, but expensive with short cord.

Numatic International
Henry Canister Series
Budget king, super durable, but heavy and poor on carpets.

SEBO
AIRBELT D4 Premium
Durable, powerful, long cord, but heavy and pricey.

SEBO
FELIX Premium
Durable, powerful, good for allergies, but heavy with awkward attachments.

Miele
Classic C1 Cat & Dog PowerLine
Durable, powerful, quiet, but very expensive, short cord.

Ranked #1
SEBO - AIRBELT E3 Premium

Ranked #1
SEBO - AIRBELT E3 Premium

Ranked #1
SEBO - AIRBELT E3 Premium

Ranked #1
SEBO - AIRBELT E3 Premium

Ranked #1
Numatic International - Henry Canister Series

Ranked #1
Dyson - V15 Detect Series