What 50mm 1.8 lens will auto focus on my Nikon d5100?

What 50mm 1.8 lens will auto focus on my Nikon d5100?

The AF-S G model will. It is about $100 more expensive than the AF-D model.

Any Nikon AF-S lens will auto focus on your D5100.AF-S 35mm f1.8G, AF-S 50mm f1.8G, etc. As long as as you buy an AF-S lens it will auto focus on your D5100.

As others have said, the AF-S model will autofocus, the cheap AF-D one won't.

If you are looking at it as a "standard" lens, the 50mm was really considered "standard" on film or full-frame bodies. For a DX camera, the 35mm f1.8 would give the same field of view as the 50mm used to on a 35mm film camera. You might find that the 35mm f1.8 AF-S is a better bet - unless you are looking for a cheap-ish portrait lens, in which case the 50mm f1.8 AF-S is indeed pretty good.

Another option would be the 40mm f2.8 Micro AF-S lens. You lose just over 1 stop, but it's a nice sharp lens and gives you proper 1:1 macro close-up. (Micro is just Nikon's name for macro!)