Wedding Guest Attire??

My boyfriend’s friend is getting married next weekend and I’m trying to figure out what’s appropriate to wear to the wedding. It’s a barn wedding and they recommended maxi dresses/skirts and sundresses for the ladies.

Can anyone give me some insight as to which I should go with! Thanks in advance!

*** My mom loves #1. She says elegant but I think it’s kind of matronly. It is flattering though.... Help!

I’m 19 and while I personally like #4 the best, I don’t want it to seem too young. Does it give off that vibe, or am I overthinking it?