Also, a 9mm is plenty in a self-defense situation. It is a smaller round but it is the smallest round that has still been proven to cause hydro-static shock to a person being hit in the vitals. So in my opinion go with the G26; cheaper ammo, lighter recoil, and it will still get the job done.
When my wife was looking at her Glock the gun salesman said the same as the other posts but instead of trying to sell the gen 4 for the higher price he said that with the 9mm it has the potential of not resetting back to place due to the new recoil spring and guide rod. Not a lot of difference my girl felt withe grip of the gen 3 vs 4. She chose the gen 3 g19 vs the 26 because she liked having a bigger grip and that the baby Glock hurt her palm due to the shorter backstrap. If u can rent them and fire it. My opinion is to go with the gen 3.