If you are in tank spec and tank gear, is it better to have endurance augments or go with the Defense rating augments?
Mitigation augments are always better than Endurance augments. In fact, until you get into full DG gear, mitigation is always better than Endurance and, even then, it's a break even and so depends upon your personal preference.
As to which mitigation augments you want, it depends. You want to get to ~30/65/60 for you listed chances. If you're shy Defense, you want to use Defense augs. If you're shy Absorb, you want to use Abs augs. You should *never* be short Shield, so you shouldn't ever use Shield augs.