I have to agree with VampireKangaroo. Spawn has some of the best art in the comic universe and a deep character who spans multiple universes and times with storylines all over the place. Spawn the pin could pull from the voices in the HBO series for pretty cheap (I'd imagine). I think Zombie Yeti could pull the artwork off if McFarlane was too expensive or unavailable.
The problem is licensing. McFarlane and Neil Gaiman have only just resolved a decades long feud over Angela/Cogliostro/Medieval Spawn (https://www.hollywoodreporter.com/thr-esq/spawn-comic-book-todd-mcfarlane-neil-gaiman-286071). There is a ton to pull from in the universe like Violator and all of the past iterations of spawn (like Pirate Spawn!) but it'd feel empty without Angela and Cogliostro. They added depth and character to Spawn that didn't exist prior to it.
Add to that the fact that McFarlane is willing to go to court for 20 years over licensing issues and I'd think that would be enough to scare any pinball company away.
So... maybe a Squirrel Girl pin? I'd love to see a pin with universal acceptance that leans more towards girls/women. Pinball manufacturers need to make money and I understand that pinball is a male dominated sport, but I feel like it's a catch-22 situation. There are no pins that target women. If there were, would more women join the sport? If pins targeted the other 50% of the population... would it become more popular? I think we're ready for it.
If not, does Rick and Morty count as comic characters? Cartoon, comic, and soon to be Dungeons and Dragons characters/universe. R&M is quickly moving up my list of dream themes (behind Harry Potter and The Princess Bride now that Deadpool is here).