I'm fond of the Canon CanoScan LiDE models for general use. They are relatively inexpensive and completely USB powered (just plug the scanner into the USB port and it's ready to go). They are also fairly lightweight and use a row of LEDs on the scan bar for the light source, meaning that they are fairly indestructible. They don't come with fancy extras like document feeders, but I guess it's a matter of usage patterns. I mostly use mine for doing salvage scans on old photographs (48-bit RGB scans at 1200+dpi to ensure that I get all of the information in the photo; it's easy to reduce, but hard to get back lost detail), but it also works well for scanning handwritten pages and the occasional flower, insect, or slab of meat.