Must admit to never getting over to Busch Gardens in 4 Florida visits (shame on me..!!)

However, I think you must visit IoA & Universal.
IoA, whilst in my opinion being a bit teenage oriented, has some great rides.
Universal, I found to be really enjoyable this summer. The newer rides (Men in Black, Mummy & Shrek) have livened the place up and in Lombards Seafood Grill they have one of the best restaraunts in the parks (the Fish & Chips enjoyed by my daughter was the best I have tasted..)
Dependant on what time of the year you go, it may be worth investing in the additional 'Express Pass' which gets you to the front of line on all the top rides. (i think we paid about $30 each for both parks and managed to do all rides in both parks on one day..)