I ran a PbP Fallout game from 2018-2019 using a hack for the Genesys RPG focused on a group in the Commonwealth going to start their own settlement during the events of Fallout 4. At our height I think we had 24 active players but for most of the time we had a dedicated group of 12 or 13 and it went really well.
When the game ended I told them that there would be a sequel using this system when it dropped and it’s been a frequent question over the last two years as to when the game will start up again.
Point is, if you get the right players you can get a truly great game and if you’re not sure on a location never be afraid to start with one of the games, you’ll have a lot of prep work done for you with minor tweaking foe how the players change things up.
Whichever way you go, I wish you the best of luck with it. It can be tricky at times but so much fun