I currently have the Indestructible Alchemist's Stone and Essence of Gossamer. In 25man Naxx Defender's Code dropped. I didn't really want it, but the raid insisted I take it. I think it was because some of them thought I get bonus armor from trinkets and rings still. I tried to tell them I didn't want it, maybe because I ran H AN about 30+ times before EoG dropped and I don't want to part with it. But anyway....
I am pretty unsure which is better for me. To compare, its about the difference between, unbuffed, a bit over 1% physical damage reduction and 11.5% dodge for 20 sec vs. 1500 hp and some damage reduction. Never really noticed how much the proc ability helps so unsure of its real benifit.
Maybe they are better in different situations. Thanks in advance for any comments and advice. I wouldn't check armory cause I logged in resto gear.
Different situations require different things, keep both. In general, Essence of Gossamer will likely be more useful. However, in some situations where melee hits might hurt a bit too much for even a plate wearer, you might consider using Defender's Code and Valor of the First War in order to sharply up your avoidance during the fight.
Yep, if possible, a tank should try to collect different trinkets. Swapping out trinkets is one of the easiest ways to tweak your gear to tailor it to a particular encounter, for more effective health, threat, or avoidance.
Generally, I prefer stamina trinkets when I'm MT in progression fights. But there may be fights where you might want more avoidance, so it's not a bad idea to keep a couple of good avoidance trinkets in the bag, especially if you can pick them up DKP-free and they would otherwise be sharded.