I would agree that 417 is certainly easier, though it sure seems like you're paying a lot of tolls (must be at least $6 or $7 between WDW and the airport)! The airport is very close to the exit/entrance for 417. The road to I4 is slow-going (lights, shopping, intersections galore). If you're travelling during light traffic time I4 will save you money and isn't any longer time-wise or distance-wise.