Pinball Champ 82 is one that is overlooked. It’s a fun game and if you can track one down, they don’t cost a fortune. I know there aren’t a ton of them in the US but it’s certainly more accessible than say Spooky.
Just about any game from 1978-1983 is overlooked in my opinion. It was the point in Pinball where games that were released were made in much smaller number because vids were taking over. It’s one of my favorite times in Pinball.