Orlando Premium Outlets is absolutely your best bet on I-Drive. (It's south of Sea World, in the newly developed area.)
As a local, I have to say that Mall at Millenia is the most over-rated useless mall ever -- unless you're insanely rich. When it first opened it was the place to See and Be Seen. Now it's the place to forget, lol. It's all Channel, Louis Vuitton, Nordstrom's, etc. I will say that the Macy's is WONDERFUL, but it's the only thing in the mall with any kind of actual value for the money.
Festival Bay will be a wonderful mall when it fills in. At the moment it's got a beautiful Cinemark movie theater, a Ron Jon's surf shop, and a Bass Pro shop, among others. (Be sure to grab yourself a float from the A&W Root Beer!) It's owned by Belz, and sits at the edge of the Belz Outlet complexes, so it's worth a look if you're headed there anyway, or have a special interest in the existing shops.
I've only made it to The Pointe once, and was not impressed. There seemed to be more empty spaces than actual shops. The Dapy store is interesting and fun, but there's another location at Universal's CityWalk, so don't make the effort here. There is no parking beyond the badly laid out (and expensive!) garage, and your ticket is only validated if you eat at a table service restaurant with a bar.