I have been to Thorpe and Blackpool but they both have pretty bad atmosphere, things looking in a bad way. Alton Towers seems to be very magic and different, it is also THEMED.
Thorpe is themed. Some areas of Blackpool Pleasure Beach are too.
Thorpe park is basically a British island with a lost city, a volcano, a cove, a village which has been attacked, a creek and saw is there somehow...
As opposed to Alton Towers which is a British house and gardens with a pirate cove, a canyon, a forest full of graves, a monster in a crater, a big hole, a race track in a dark forest and Ice Age is in there somehow.
Whilst I'd say that overall, Alton Towers' theming is superior to Thorpe, I don't understand the point that you're trying to make about Thorpe as you yourself have highlighted the various themes which they have. Also I fail to see how anyone can accuse Thorpe of not being themed, there are several themed rides and areas around the park and, apart from maybe some of the Tussauds flat ride, I can't think of any of the park which is unthemed.