I have visited twice in the last couple of years for both 14 and 21 days, and having been before, I would say I would be able to do 'the best' of Orlando in 5 days OR 'the best' of Disney in 5 days, but I wouldn't take a crack at both. Should you try and do both ticket prices rocket also, as whilst a FlexTicket or Magic your Way ticket is good value, for 5 days it would be a lot of money to buy both, probably unnecessarily. I would say:
Day 1, Magic Kingdom
Day 2, Epcot
Day 3, Animal Kingdom (am), Blizzard Beach (pm)
Day 4, Hollywood Studios then Epcot in the evening if not bothered about Fantasmic!
Day 5 & 6, Universal Parks OR your favourite Disney Parks
Adding the Universal Parks does increase the price a fair amount for the above itinerary, but they are a must do. If Disney doesn't bother you, then skip Disney altogether to save costs and just focus on the Orlando attractions and maybe Busch. In terms of transport as well, I'm not sure what you were planning or where you aould be staying, but Disney transport is OK to rely on should you be staying in Disney, otherwise you would need a hire car.
Day 1, Magic Kingdom
Day 2, Epcot
Day 3, Animal Kingdom (am), Blizzard Beach (pm)
Day 4, Hollywood Studios then Epcot in the evening if not bothered about Fantasmic!
Day 5 & 6, Universal Parks OR your favourite Disney Parks
Adding the Universal Parks does increase the price a fair amount for the above itinerary, but they are a must do. If Disney doesn't bother you, then skip Disney altogether to save costs and just focus on the Orlando attractions and maybe Busch. In terms of transport as well, I'm not sure what you were planning or where you aould be staying, but Disney transport is OK to rely on should you be staying in Disney, otherwise you would need a hire car.