Best carpet cleaner?

[speakout]

I need to clean my carpets in several rooms, I have hired a Rug Doctor in the past but would like to buy a machine.
It needs to clean stair carpets too.

Any reccomendations?

Bumping as in the same situation now! Well, never hired a Rug Doctor...wondering whether it's worth investing £100 in a VAX type carpet cleaner machine instead?