Personally? I would go play the seasonal servers, which I am playing. I would also play other games, and other versions of the game, which I do.
If I was looking for a long-term home on Classic Era servers to play with others who were doing the same thing, I would most likely look into the adventures of Jarl from Grobbulus and see if there would be a place for me among their crew…
On the other hand, if I was continuously chasing a fresh experience, but within the more-or-less OG Classic Era world of Azeroth, I would have a look into what Alodar is stirring up over on Deviate Delight
If on the other hand, I wanted to play with others on the largest clusters, I might check out Whitemane and either make some goals for my characters and go for them, or just hang out.
One thing I wouldn’t do is hop into WoW Classic Era, wanting new content and expecting to find it there.