For me, Blackpool Pleasure Beach has transcended being a mere amusement park by the respect that it has shown to the heritage of its rides, several of which are from the 1920s to 1950s (the Fun House would still stand too if it hadn't burn down). It also weaves some rides in and out of each other, creating more of a sense of an overall design plan than some amusement parks might have. This makes it a true theme park to me, one of the themes being being a sort of historical survivor of the golden age of wooden rollercoasters.
Alton Towers' concentration on extreme rides doesn't fit especially well with the country setting (The Ultimate at Lightwater Valley showed magnificently how it can be done, although the rest of the park has sadly stood still or declined since its 90s heyday). It's ironic that Alton Towers neighbours have long scuppered a tall wooden rollercoaster ever being built due to noise and visibility - such a rollercoaster would actually respect its setting much, much more.