I have the Titan canister. I have tile, hardwood and a few large area rugs. I have a seperate head for tile and hardwood and a powered head for carpet.
I grew up with all uprights and wasn't sure about a canister, but I really like it.
I have the Ariel. We have hardwoods, some area rugs, and tile in the bathrooms. I really like my Miele. Like rehabaddict, I wasn't sure I would like the cannister at first, but I really love it. It's easier to maneuver under furniture and in tight places.