I'm partial to Fujitsu ScanSnap document scanners. It's worth paying the extra money for a Fujitsu, imo.
The only catch is that you are supposed to replace the pick roller and pad assembly every year or so.
I would recommend buying a couple of extras in advance, as they will get harder to find and more expensive as time goes on.
Having said that, I didn't replace my pick roller/pad assembly until after 9 years of operation. After a few years it would have trouble feeding multipage documents, but most of the stuff I was scanning was only one or two pages. When I did eventually replace those parts, the scanner was basically as good as new.
