UO without stacks is worth about 172 stamina work of EHP. Sind's fang is 228 for the non-heroic. In terms of raw EHP Sind's fang is significantly better, so honestly it depends on your playstyle and the playstyle of the healers and what content you're doing. For most fights, it's really not going to make a huge difference which ones you decide to roll with. If your healers start to struggle a bit, then go with the armor trinket. If your healers have no problems healing you up and you just need more EHP, then go with Sind's.
Example: I did a marrowgar 10 PuG the other week and the healers and DPS were TERRIBLE. As a tank I was beating 2 of the 6 DPS and the highest DPS was like maybe 4k. The other tank was pretty bad too. The healers just couldn't keep up so I swapped to double armor trinkets to try and make it easier for them even though technically it was less EHP (went from ~ 34k unbuffed armorf to ~39k unbuffed armor).
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