New to Online Multiplayer

Hey all, I made a post a couple of months ago about how after two years of awfulness, i managed to get my life straight and bought a PS4.

So many people were supportive and kind, i got lots of comments and recommendations for what to play.

Now, i want to play some online multiplayer games, but aside from COD, I have no idea which games have active, busy player bases. Genre of game doesn't bother me too much, i just want to try online multiplayer out properly.

all game suggestions would be hugely appreciated! thanks my dudes and i hope we're all well