My absolute favorite is the rounded french cuff with the cuff and collar being of slightly stiffer than normal material to give it that crisp and solid look, however I usually reserve that for more formal ocassions. If your shirts are going to be worn without jackets, I think 1 button barrel cuffs are the way to go, though I sometimes wear french cuff shirts without jackets.
If you don't have a strong sense of what you want going in, you should just get standard one-button rounded barrel cuffs. You may regret it later if you get something more unusual and decide you hate it after wearing it for a while.
I wish they had elongated the cuff for the double buttons so the proportions looked a bit better. I tend to prefer my double-button single cuffs with a beveled, not rounded edge, but honestly, few people are going to notice much of anything. They look fine. Buttons look nice in shot 2.