I've had the Shark Navigator Lift-Away Professional for two and a half years. It replaced my previous Shark.
One thing that would make me happier is if I had the better cord, the no-kink one. But it is a longer cord than my previous Shark, so I can *almost* reach every corner of my house from one electrical outlet.
I mostly use it on hard floors and mostly with the Lift-Away so I can just vacuum around clutter. But when I vacuum our bedroom rug it is very satisfying. I think lots of carpet would be fun.
But removing hair from the brush isn't too easy - it's fine for me but if I actually used it a lot I'd prefer the one where you can take it out to clean.