Too hard, that is why my collection is out of control! I like them all! I'll put them by category like the academy awards:
Sentimental - Aladdin's Castle - the one that started it all.
Art- Mata Hari
Challenging - Houdini
Game night favorite - Munsters
Best executed theme - CFTBL
Best movie theme/integration - Goldeneye
Best "just one more game" - Black Knight (honorable mention - Space Shuttle)
Best EM - Fire Queen (combo of graphics and game play)