What handheld vacuum cleaners are everybody using?

[Dano]

Looking to get one to supplement my robovac and give the stairs a quick once over every week or so, what is everybody using and what should I avoid? Thanks

 

[Dano]

EDIT: actually, not what I'm looking for, I want a handheld one, not simply a cordless full size vacuum so any recommendations would be great.

Hmmm, odd that didn't show when I searched... thanks