Sky Jump is at the top of my list. It's all about lining up the 10x with the lit drop target. It really sets it apart. I had no idea what to expect when I bought mine, as I'd never played it before. It will never leave my collection unless I find a better example.
My top 5:
1. Sky Jump
2. Pin up/king pin
3. Abra Ca Dabra
4. Atlantis
5. El Dorado