Tilapia, red snapper, flounder, cod, farm raised catfish are all pretty mild fish.
Another way to prepare fish that allows for alot of seasoning is poaching.
Throw some chicken stock in a pan (and some wine if you want) choose your seasonings (works great with fresh herbs.) make sure that there is enough liquid to cover 2/3's of your fish and put a lid on it.
Your fish will be cooked in probably 3-8 minutes depending on the size and amount. It comes out flaky, moist and generally takes on the aromatics that you use to cook the fish in also (so less fishy.)