Coin flip.
If for an anniversary - Yachtsman may have marginally better ambiance.
But unless you are on
Disney Dining Plan - you may want to look at Swan & Dolphin Signatures. The food is (likely) better than either Yachtsman or Flying Fish. All have better ambiance than Disney Signatures.
blueZoo is our favorite.
Shula's can be intimate, but also male-centric with footballs.
Il Mulino can bustle if arriving when bar/lounge gets filled with convention'ers.
http://www.swandolphinrestaurants.com/