Bulwark and bastion enhancements don’t steal as much from the shield/absorb so are less punishing in sub-75 content. I think top level tanks could probably make a compelling argument that steadfast or vigilant enhancements are superior to bulwark/bastion/sturdiness/immunity enhancements in 75 content, but in my personal opinion, since I do a mix of all types of endgame content and sub-75 stuff is overwhelmingly represented, the advantages don’t outweigh the loss of defensive stats which won’t be penalized in level lock.
The extra critical rating may have a measurable benefit, but it will be mostly in sub-75 content. The one exception to this is Efficient enhancements. If you are a dual wielder the extra accuracy could in theory help your off hand hits, but the increased chance of hitting doesn’t really make up for the loss in baseline damage from the power loss. However, unless you are aiming for the 1.4s GCD the extra alacrity rating is largely wasted, and the extra accuracy is pretty much wasted. Some R numbers of these high endurance that have larger stat pools than the basic ones (no R number.). If they do it’s probably as a buffer until they can get better gear to do their jobs correctly and learn the mechanics, and it’s exclusively only useful in 75 content and actually harmful in 70 content. DPS/Healers almost never need the extra health.