1 - PortAventura: I love this park, the atmosphere is incredible and more vivid at night! It's got a lovely magical feel about it, nearly on par with Disney's parks in my opinion, and the ride selection is great! Dragon Khan alone is worth the visit. The park does have it's flaws, like graffiti everywhere and a mediocre flat ride selection, but that doesn't matter, PortAventura is a growing park and it's only going to get better! Personally I'd think a Flying coaster would fit the park perfectly, more so than the rumoured Dive Machine/Hyper coaster.
2 - Alton Towers: Alton has to be Britains gem in terms of Theme Parks. It has an authentic British feel, lots of green, lots of ducks and most evidentally lots of grim theming. I mean seriously... We have: Forbidden Valley, Gloomy Wood, X-Sector, The Towers and the Dark Forest, in which pretty much all of the iconic rides are located. The thing that completely makes Alton Towers (not much in recent additions) is the creative use of it's restricted tree height, still baffles me when I read: 'Height: 65' Drop: 180''. Shame the Towers have been going downhill since AIR (in my opinion), need something hard-hitting soon!
3 - Disneyland Paris: What really makes a great park isn't to do with ride selection, sure you can have the most intense rollercoasters in the world placed on a car park, you'll have great rides, but thats it! Disneyland parks are the pinnacle of theming. And they look outstanding, at times they look like you're on another planet, but the incredible effort put into these parks to look the way they are is a feat on it's own! What stands out the most for me in this Disneyland, is the rollercoasters, I think they're brilliant, in comparison to the Magic Kingdom in Florida specifically, you can really tell the advancement here.