Heading back to Florida end of October. It'll be my forth time visiting. Fantasic place.
Disney parks are superb for kids. Best thing in the world to bring kids to. If you don;t have kids don't bother.
For Rollercoasters busche Gardens (half theme park half zoo) and Islands of advernture would be the best imo. Superb parks.
I haven't been to Universal Studios of a few years (was in the L.A. one in January this year). Would not be my favourite park tbh and would not have the most extreme of rides.
Don't discount seaworld. This is a superb park with a good few rollercoasters. This park is owned by the same owners of Busche Gardens so you can buy a good value ticket for both.
Please note all the parks are in the Orlando area except for Busche Gardens which is in Tampa (about 1 1/2 hours drive).
One other thing check to see if Universal or Busche Gardens are doing the Holloween party's while your there. I have booked tickets for our trip in October. It's supposed to be excellent. Runs from Sept - Nov.
Finally this place is supposed to be excellent for tickets: