I like Perry Rhodan a lot.
If you’re not German, and even if you are German, you might not have heard of Perry Rhodan, so here is a quick high level summary. Perry Rhodan is a German pulp magazine sci-fi series. It has, somehow, been in continous publication since 1961. It is still very much published as pulp issues - at time of writing, we’re on issue #3226. This makes it probably the longest continuous story ever written. The series is written collaboratively by many authors taking turns with overarching guidance from a core team.