I have a Polaris 280 which performs very well but if I had it to do over again, I'd probably go with a robot such as the Dolphin or Aquabot.

The robots are at least as good as and probably better at scrubbing and vacuuming the bottom and walls and they have an effective filtering system that supplements your main filtering system to "polish" the water. When you take into account the cost of the booster pump and dedicated return required for operation of the good return side cleaners (e.g. Polaris 280 or 380), the cost is fairly comparable to a robot.