IMAScore's stuff is very basic (as in the track tends to follow a simple set of chords), but it's also catchy and pretty damn memorable... Stuff like Krake and Smiler are like this...
Then you have stuff like Helix, Chiapas, Magic Valley at Toverland and Klugheim, which are a great combination of that same technique but those work immensely well in the context of the rides and areas themselves... They're probably slightly better in terms of producing a complete package of music for an entire area rather than a single track, as the difference between them is much more noticeable in those senses... It's like Disney soundtracks for certain rides in a way...