For us:
Must Do - Kong, Spiderman, Doom, Cat in the Hat (no line, very cold, great for hot day), Trolley Ride (great views), Hogwarts, Minions, Transformers, Fallon, Mummy x2, ET, MIB, Horror Show, Gringott's
If we stay multiple days on site, we always spend half day on water rides in bathing suits. Know for your one day excursion the Dudley and Popeye will get you soaked, like stand in the shower wet, Jurassic gets you wet, but not soaked.
We will ride the "roller coasters" from time to time, but we live close to Cedar Point, so the magnetic draw is not there for us - don't get me wrong, they are good coasters, but not must dos. Mummy excluded, it is awesome and always gets multiple rides - a true class of its own.
We LOVE all of the simulator rides. Again, as multi year annual pass holders at Cedar Point, it is like saying all coasters are the same. Or, for Disney fans, it's saying that Mermaid, Nemo, Small World, Frozen, etc. are all the same ride because they are slow moving vehicles/boats going scene to scene through well known and adored IPs.
For us, Spiderman and Transformers are very different rides, but we also go opening weekend to every Marvel and Transformer movie. Kong was just awesome to us, still not sure I have seen every detail, and we have rode dozens of times, but I also watch Rocky AGAIN this weekend and can't believe Creed won by split decision. We want to "Ride the Movies" and love them all, it's just personal preference.
You only have half of a day (after HP lands), make sure you really think about what you like and look over the maps and have an awesome day!