Dragonfist is severely underrated. It deserves to share the spotlight with Star Gazer, Sea Witch, and Quicksilver.
Spirit is a blast to play but I can totally understand why it's not everyone's bag. Same thing with Hercules tbh.
My favourite rare EM is Balls-A-Poppin, which has a crazy multiball gimmick and is built into a bingo cabinet.
Andromeda has an awkward layout imho. But amazing sounds and art.
I love AMH and the open-source spirit.
In that vein, I really really want to try Captain Nemo. (16 made, right?) the code for that was also open-sourced.
of the newer games, Alien and Big Lebowski for me please, and I truly hope they become as common as AFM.