The 3 different sizes you talk about are more squares on the die. So, bigger die, more squares and more expensive. That's why the Super Giant is the most expensive. There would be less waste with the Super Giant, but with square dies(not an odd shape) there isn't much waste anyway. If you're looking to do this for resale, I'd go with the most squares on a die I could get which would mean with the super Giant you could get 80 squares with one crank.
As for pinked edges. That's a personal thing, I guess. I hate them. I hate the dust they make, the seam allowance tends to be harder and just the general use of them. But, that's up to you.
HTH.