Of my Kirbys, I'm kind of partial to my G5 "Frankenkirby" because in fixing it up with oddball parts (Sentria brush roll, Ultimate G bag and emptor assembly, and the G4 handle back that it already had when I got it) it's developed a character all its own. Call it "bojack" if you must, but I still like it. The two G6s are great machines as well and all three Kirbys clean equally well.
It's a much tougher call on the Electrolux canisters. Even though I prefer to use the Super J because it's more powerful and its pimped out gold "Superfly" paint job is actually growing on me, I think I'll always have a special attachment to my teal 1205, complete with all its teal attachments simply because I've had it the longest of any of my current vacuums.