I growing up, we were pretty much brand agnostic when it came to vacuum cleaners. The earliest one I remember was a pink and gray Lewyt canister, which was replaced by a tan and green "Brady Bunch" Hoover Convertible, and later with an uber noisy Singer upright. There was also an Electrolux 1205 (sans power nozzle) in the mix that Dad pulled from a neighbor's trash pile. The canister worked great but the hose leaked like a sieve.
As for my own preferences, Kirby is the clear winner for uprights, and I use mine strictly in the upright configuration. While it's cool that they can sort of convert to a canister-like configuration--a feature that impressed me mightily when I saw a Classic Omega demonstrated when I was about nine years old--I now see that they really aren't all that great as canisters; in fact, they're terrible and that's where my canister of choice come in.
That particular honor goes to Electrolux, specifically the 1205 and its immediate successor, the 14xx series (aka, Golden Jubilee, Super J, Olympia One, and Silverado) all with power nozzles, of course. Honorable mention goes to the power nozzle-equipped metal Eureka canisters from the '70s.
For Electroluxes, my power nozzle of choice is the PN-2 with the PN-1 as a close second, almost a toss-up, really. I've never used a PN-4, so I can't comment on that one, but I just don't like the L-shaped design of the PN-5 and later nozzles. It may be because I'm left-handed and the 'outrigger' is on the wrong side for me, so I'm constantly snagging it on furniture legs and such. I strongly prefer symmetrical designs. Try using a butter knife with your left hand and you'll see what I mean. There's no excuse for them to be designed that way, none at all.