I would like more guild competition so 500+ would make me happy honestly. I've played on a decently sized midrate before it closed down (supposedly reaching over 1k for woe's before server pop declined due to corruptions), and a lowrate with over 2k pop. I love big WoE's, it makes alliances matter more, and also not knowing everyone and their dog makes it nicer to actually meet someone.
Also means GM's could kill @main if server actually got big enough, and we all know how this mod personally feels about that *-*