If you have a crop body a 35mm is infinitely more useful than a 50mm unless you pretty much only do head shots or regularly have a lot of room to back up. I was in the same scenario and ended up going with the 35mm. Take your kit lens and really study each focal length and imagine it doesn't zoom. Try taking pictures with those limitations and see if it impairs your ability to get the shots you normally take.
Just looking through your pics and seeing what focal length you use isnt the most accurate method imo, as there are times when you could have zoomed with your feet, but just didn't b/c you had zoom ability. So maybe you do have the flexibility of a certain focal length, but just dont know it looking through your old pics.
FWIW...