Watching just the first season of Stranger Things was probably the right way to do it. The first season is a complete story, and all the other seasons just feel like Netflix milking its success for $$$.
Other shows where you can watch the first season and stop for similar reasons: Handmaids Tale, Westworld.
So, S1 of the expanse was my favorite season by far, mostly because I loved the introduction to the belter ethos, it set a tableau for the rest of the season which was much more action oriented.