seems like the first topic of feedback is payload/etc. etc. However, IMHO there are a few other differences that could sway you one way or the other. My observations.
1) Many 1/2 ton "crew cab's" have a shorter std box than a 3/4 ton. less cargo room.
2) Many 1/2 ton are shorter overall than the comparable 3/4 ton.
3) Many 1/2 tons have a lower step in height than 3/4 ton.
So, before deciding just on payload etc. look at the box length, interior room, overall length and decide what fits YOUR needs and wants best.
For us, a long enough short box to haul motorcycles or loads of dirt, a large back seat to take 5 adults comfortably was high priority, and I sacrificed overall length, and step in height and turning radius and went with 3/4 ton. But again that was OUR priority, decide based on YOUR priorities.