They come with a regular hammer, a bobbed hammer or no hammer.

I got the no hammer because I carry mine in my pocket. It's a real bitch to reliably draw a gun with a hammer from your pocket at all, much less under stress. The bobbed hammer would be okay but in a defensive situation the last thing I will ever find myself doing is pulling back a hammer. I'm just going to pull the trigger. Also, I'd never use that feature at the range because I wouldn't want to train with a different method than would be ideal in a defensive situation.

A hammer would be good for strictly a range toy or if you are going to ankle carry since most ankle holsters have a retention strap and the hammer will give it something to strap with. Obviously that is not the reason it is there but that'd be an extra bonus if you went that route. Of course, I'm not a fan of ankle carry at all but that is a whole different topic.