Hmm a 3 yr old? Kiddie rides, for sure.
IoA: Suess Landing, for sure. Lots of kid-type things there, and even adults have fun! My friend and I both went (and we're teens) and we liked it! Lost Continent, try Flying Unicorn roller coaster. Not sure on the height requirement, but it was really fun for a kiddie coaster! Try it if your DD is daring and tall enough. Jurassic Park might be too intense, but check out Camp Jurassic. Toon Lagoon has Me Ship, The Olive, which is a fun, interactive boat (i.e. Donald's Boat in Disney). Marvel Superhero Island really is for teens/older kids/adults.
USO: Let's see, Woody Woodpecker's KidZone is a MUST! Barney, E.T., Fivel's Playland, Curious George Goes to Town, and Woody's Nuthouse Coaster are here, as well as the Animal Actor's Show. Also, check out Jimmy Neutron (stationary seats) if she likes Nick.
I'd say, try Universal out! You won't regret it, that's for sure!