Which version and server of WoW Classic would you recommend I play on?

Hello everyone,

I’m new to the World of Warcraft universe and a friend has recommended I try Classic to enjoy the original experience, which I prefer because I’m coming from EVE Online and I like long-term adventures. However, I see that I can play Classic Era, Season of Discovery, The Burning Crusade Anniversary and then Mists of Pandaria. I’d like to know which is best for a new player to start with, and which servers have the most active players, as ultimately this is a collaborative game and if I can’t find any players on the server, I’m fucked.

Which version and servers would you recommend I play on? I can speak English, so language isn’t a problem.

Thanks!