As much as I may love Electrolux, I would NOT give my vote to the new Aerus vacuums. Of the three, I would pick the Sebo D4 canister. I have a Miele Monte Verde w/SEB217 & Red Velvet w/SEB236, & a Sebo Airbelt C3.1 with ETC PN. Of my Electrolux vacuums, newest ones I have is the 2100 w/PN5 & Grand Marquise w/PN6. I have tried out the Guardian Ultra recently, when I had my AP280 in the shop for repairs....while it was a good vacuum, I was not really that impressed with the suction power or cleaning performance. It was OK, but not on a par with the Miele or Sebo vacuums I own. Plus, it is much louder than either the Sebo or Miele. I also have not been impressed in the past with the wands on Electrolux vacuums....they do have a tendency to burn out & need frequent replacement, as well as the PN neck. They should have stuck with the original Guardian....it had more user-friendly features, & had the features & quality you expect to see on a vacuum worth $2,000.
Sebo, on the other hand, is MUCH better made. The electric wand & PN neck does not have the issue of burning out like Electrolux vacuums do, & it is also a telescopic wand. Suction power on my Airbelt C3.1 is very close to my Mieles, & the new D4 models are supposed to be rated higher than the Mieles, at 110 inches Waterlift, vs 100 inches Waterlift for Miele. The cost of supplies for Sebo vacuums is right in the middle between Electrolux & Miele....not inexpensive like Electrolux bags are, or as easy to find, but certainly not extravagant like Miele supplies are- you can EASILY spend $60 for 1 Miele HEPA filter. Plus the bags on the D4 look to be the biggest of all three vacuums. The main disadvantages the Sebo has would be the lack of availability of generic supplies, & they don't have as much features as Miele or Electrolux vacuums have- you can't get a lighted PN for a Sebo, nor a mini powerbrush like you can for Electrolux, & they have the on/off switch on the PN vs on the handle. Yes, the Miele would be comparable in quality to a Sebo, BUT for me the deciding factor would have to be that Sebo markets the D4 in a commercial version for professional use....you can put all the fancy warranties you want on a vacuum, like Electrolux & Miele do, but the REAL TEST of a vacuum is if it's made to stand up to punishing commercial usage, which the Sebo would definitely be able to handle.
If you do insist on an Electrolux vacuum, though, I would suggest looking at the Perfect C101 metal canister, which is the copy of the Diamond Jubilee & Marquise vacuums. I have heard they have some issues, & they are made in China, but they are better built at $900 with a double-stage motor than the Aerus Classic for $1,000, & based on the one I seen in person, I felt they had reasonable build quality. Plus, their cleaning performance is even better than Miele, Sebo or Electrolux, since their motor pulls 120" Waterlift, & you can find HEPA bags for the Perfect or any Electrolux vacuum for very reasonable prices.
Rob