Personally, I like the second one the best.
If you genuinely love one of the other dresses, then get that dress. However, a lot of people get second thoughts just because they look at other dresses after they've purchased theirs. Dress envy/uncertainty is bad! You have to love it.
Here is the rule: Pick your dress, and stop looking. I guarantee you that there is probably something better out there *somewhere*, but if you've made a decision and purchased it, you will be so much happier if you just never look for another dress!