My first caharcher was a Night Elf Hunter on a PvE server, and so I was Alliance. My second character was an Orc Warrior on a PvP server on the Horde side. Since then, I’ve played both sides almost equal.
In Forever, if you pick PvP, then you are locked to one side; on PvE, you can play both Alliance or Horde on the same realm.
This, of course, means I need to pick a side.
I’m still not sure.