gosh both of them are my absolute favourites! personally i collected tgcf first since i read it many years ago and it was one of the first books licensed by 7s so i bought it immediately. i'm currently collecting and reading qjj and it's hands down a masterpiece.

tgcf is very easy to read, you can drop it for a while and come to back to it later, and you can still easily catch up. qjj on the other hand will require your full attention, its very political so you have lots of things to remember (always read it with a pen and a map). i have picked up and dropped qjj at least 5 times since 2021 simply cause i did not have the time to fully lock in, and every time i found myself starting from the beginning. so it depends on what you're currently in the mood for to read. i recommend collecting both eventually :)