Definitely the best for me is Meile TT Cat & Dog. I have this for nearly 2 years and it still has the perfect suction that it always had, even with dealing with a hairy golden retriever.
There has been threads on here before about vacuums, so have a search.
Miele or Dyson.
+ 1 for the nilfisk, i actually got mine for free on freecycle when i bought my house as i couldn't afford one 3 years ago as a stop gap measure & its still going strong.We have a really good Nilfisk one with an allergy filter (I have asthma so it keeps dust at bay) and it's bloody great - cost about €200
Thanks for all your replies. You have made my search so easy. Looks like Miele is the one. Had thought of Dyson, but after all the positive feedback about Miele, I will hit the shops at the weekend.