My husband and I are planning our BIG Orlando trip for this September. We will be doing both parks, one on Thursday and one on Friday. That being said, my friend and her husband (from Tampa) will be coming up to go to one of the parks with us on Friday, neither have been to Universal. SO! If you were choosing which one is best for adults and gets the most bang for your buck, which would you choose? Keep in mind, we will not be staying for HHNs.
For big ride fans, IOA would be better. Best ride-based bang for your buck
If you are interested in HP, you should get the 2-park ticket so you can do the HP areas in both parks.
The coasters in IOA are great, and Spider-Man and Harry Potter & the Forbidden Journey are really great track ride/simulator hybrids, …but if they are into Harry Potter, they would really be missing out by not going to US to see Diagon Alley - the level of detail/theming/immersion in this area is incredible!
Another vote for IOA. Its so much more visually appealing to me, and you can have lunch or dinner at Mythos! Forbidden Journey alone is a reason to go to IOA.
IOA is my favorite of the two parks but Diagon Alley is the best of the two Harry Potter sections. Depends on if they are there for rides or for Harry Potter.
Edit: That said, they will need to have a park-to-park ticket if they intend on riding the Hogwarts Express.
As a Harry Potter fan, I canot imagine NOT going on Forbidden Journey. It is the most amazing ride ever! So I say IOA.
If the weather is good and you like water rides, I’d do IOA. Otherwise USF.