I have an older Canon personally (mainly because, since I rarely scan, the thin design was as important as great image quality), but I was just reading through some reviews, and as usual it looks like Epson is the leader of the pack when it comes to quality. Canon has a MUCH better driver for their scanners, but if quality is most important, I'd probably get an Epson.
The Epson Perfection 2480 seems to be a decent scanner on the cheap (does transparencies, too), or you can go up to the 3170 if you want to spend about twice as much for higher resolution and increased bit depth.
If you prefer a better software package, I don't think you'd really go wrong with a Canon, either. Be warned that the little thin ones (Lide 80 and co) use a different technology and don't produce the quality scans of their fatter models, but they're not terrible and they get their power from the USB port, which is pretty convienent.