I’ve seen a lot of strategic variations coming from the 3 servers that just wouldn’t be possible on na head to head because of no choice on who to atack. Also having 3 teams with separate goals provide players with atack oportunities even if outmanned. My server usually fields low numbers and we would allways been pushed to defence on head to head. With 3 servers, we can grab oportunities to atack when the other 2 are engaged at some atrition fight between them.
Considering the strategic options, and remembering that your current situation is just one of possible match ups (2 strong and 1 weak), maybe you can come up with something to make the weak one atack your enemie. Give him “free” keeps from your strong enemy for exemple and avoid atacking or holding their strategic holds.
Anyway, i do think the 3 servers model superior to na head to head given the strategic variations it introduces.