Sea World basically exists because of having Dolphin Shows. I don't think Affinity is the best incarnation, but again is see it as 'dolphin shows at Sea World', in which case it totally belongs there.
Mammoth Falls I think is also deserving of its place on the list. I mean it has a very long ride time, a small height requirement, genuinely fun for all ages, is rerideable, and a has massive capacity. It was also the first of Wet "n" Wild's big modern slides and really helped the park transition from small local water park, to something quite special.
I think it's a pretty good list really. All of those attractions are not only the best the Gold Coast has, but they were also what made the Gold Coast what they are. When you look through the list, (with the exception of PA which was just perfection itself) most of those rides represent some sort of coming of age for the park they're in, and resulted in a boost which propelled the park along.
The only change I would have made would be to combine ToT/GD onto one spot and get Corkscrew on the list. While nothing special in terms of a coaster it was able to be the signature thrill ride for Sea World pretty much it's whole life. I'm glad that rides like Green Lantern, Claw and Buzzsaw didn't make the list, because while all fun rides, I don't view them as being anything 'special'.