There's various forms of scanners all around!
Are you a mobile kind of person, or prefer the printer all in ones, or you prefer a professional super DPI (dots per inch) scanner?
If it's general purposes for a home computer, either look into a flatbed and/or sheet feeder, if you want to do documents.
Office printer all-in-ones are a nice package, but sometimes they end up getting clunky because of the fact that it's with the printer, you have to use that same printer software usually in order to get it working.
There's also the handheld scanners, this is perfect for people on the go or laptops. They can look like small, thin sticks, or a larger variant of the same scanner gun you see at Target.
If you go professional type then your image scanned will come out at the best quality -- usually highly desired by graphic artists, 3d modelers, architecture.. etc. The DPI means how many dots will fit in an inch. If you get one with higher DPI, the picture will be naturally "enlarged" without losing any quality.
But putting all the above away and looking directly at your needs, I'm assuming you're wishing to scan the usual 4x6 prints.
If you prefer using the windows scanning interface, then you'll want a more common manufacturer like HP, Xerox, Epson, Cannon. Depending on which, but I don't think you will need one that runs you over 50~$100 to $150 maximum. Because if you're just scanning small photos, there's no need for a HQ scanner.
Document feeder is only important for people who like to scan like, say 30 documents without having to feed it each time. It'll suck in the next page automatically.
That's pretty much about it from me!
