The best answer I can give is do a game you enjoy. I have and have had projects that just stall out or sit for months. I currently have a Taxi I took in that needs a hardtop or playfield swap. I'm trying a hardtop and I'm finding the whole process impossible to keep on track. I don't mind Taxi but can name 5 other system 11 game I would take over it. Your enthusiasm for the game (at least for me) tends to help keep the project moving forward instead of sitting in pieces in the basement for months.