Though I am a huge fan of Stealth, the original Flying Fish is definitely missed to this day! Used to love speeding around that helix REALLY close to the bushes!
Miss Hippo's Fungle Safari is also on my list, as it really did give me my first feeling of adventure (as this was before I had my first time at Chessington). Both of these were my favourite rides at the park until they both closed in their desired years!
Must say though - Fungle Safari closed when I was 8 years old...after I had my first few times on Nemmie!