What's the best vacuum for stairs?

[NotTheOnlyPomInTheVillage]

I have Roomba, which is brilliant, but I need a new vacuum for the stairs. Any recommendations? Preferably something light but powerful, as we have pets. Thanks.

I've a regular normal Henry which is fine but what I really want is a Roomba or the likes that can do stairs! Following with hope that such a thing exists!

@svenwhen, wouldn't that be amazing? I am sure it's only a matter of time before they invent one for stairs.