I've been on the STR side for bonus points, but now that I'm at max lvl I'm starting to wonder. There have been times when a few hundred HP would give the healer the moment he/she needs to get the clutch heal off in time, so I definitely see the value in having full VIT, but I'm still unwilling to say that's simple fact because of a lack of data.

Links have been put up for how much STR is needed to increase block strength, and it's clear that 30 STR will not make a huge difference. Those links lack any data beyond that, however. The data I need to make an informed decision on STR vs VIT would be:
1. How much dmg 1% block strength will mitigate over any given fight (boss, trash, etc.)
2. How much enmity 30 STR will garner.

Particularly on the enmity point, no effort has been made to gather data (that I have seen). People say that it's negligible, but they never back up that claim with numbers, so it's purely their uninformed opinion based solely on their individual experiences.