Way to many good ones out there.
But I always try to get these 3 on all my modern games.
1. Pinnovators headphone jacks with sub output.
2. Color DMD
3. Modfather candy shooter rods.
Runners up that I would like to try or have.
LED OCD
Pinsound
Antiglare glass
Having over 10 modern pins it is just to cost prohibitive to put all of this on every pin.