As far as I know, WARs can tank all Turns in Coil (they already could, but you get the picture). I would say go VIT if you want to MT, STR if you're only OTing

I would like to hear from WARs who actually did T5 too as a WAR post 2.1. I don't feel like I can go all STR tanking Twintania, it feels I need to rely on healers more, but don't have actual proof.