I would Recommend the Splash landings hotel, much more colourful with a more Caribbean style and the music in the lifts is excellent. stayed in both hotels but i prefer splash landings, its also slightly cheaper. you can use either of the facilities no matter what hotel you stay in. Alton towers hotel is nice but seems to be darker in colours but is still good
I hear the evening entertainment is better in Alton towers hotel, however they do have a disco of some sort in splash landings and entertainers for the kids.
hope this helps
Remember you can walk between both hotels via the indoor Skywalk. Therefore you can watch the entertainment most appropriate to your group, no matter where you stay.
Having stayed at both several times I would recommend Splash Landings for families, as it is right next to the theme park monorail and has easy access to the waterpark (it is inside the hotel!).
I'd say splash landings is better.
