If you corner hard, drive aggresively, or are concerned about safety get the Hardtop. The hardtop is a superior car in these ways.
If you just cruise around the Convertible is inherently better than the hardtop when the top is down. I sold my 03 GT convertible for my 2014 Hardtop because it handled like crap and wasn't nearly as good a convertible as my 350Z. 4 seat convertibles tend to have to much wind flow through the passenger compartments.