Well, they're all *acceptable* to wear, but if you're looking for the most stylish I would say that the cargo shorts and plaid shorts are your best bet. I personally can't stand the plaid short phenomenon (makes you look a little too much like a snobbish ivy league elitist if you ask me). But, it's a hot trend right now so it would be in style. Cargo shorts have been in style for a while now, so they're fine. Athletic shorts are ok once in a while but I would generally stay away from them unless you're going to be doing physical activity that would make you need them. They tend to give the impression that you don't have style
man, I personally wear cargo and plaid during summer bc I feel comfortable with them, plaid ones are my favorites but at the end of the day what really matters is feeling comfortable with them, so wear whatever you want and don't let people judge you by your appearance.