Oh hey, what a coincidence, I just finished my first playthrough yesterday as well! Feels like there's a hole in my heart now that disco elysium used to occupy and it'll be a tough act to follow!
I went with the intellect / motorics build which was fun for all the lore info dumps, but I'd like to go for a crazy psychic build or brute strength for next time. Think I need to leave it for a while first to digest though.