30 STR nets you about a 7% increase in damage dealt. VIT either helps you stay alive or does nothing depending on the content at hand and your gear. If you routinely do Titan and Coil on your WAR I would recommend VIT, or if you speedrun dungeons on WAR and find yourself wishing for a bit more HP. Otherwise go for STR. A bit of extra damage, parry reduction, and self-healing isn't huge in a party context, but it's better than stacking a stat that's doing nothing at all for you.