That is one of the best trinket abilities-the best being the 10% heal from 'returning champion'-and still is only comparable to the passive 2% hp (based on 2000hp total) that would come from agm-even with the 5 vers. loss. It's 2% passive hp buff vs 10% hp increase for a measly 15s every 2 minutes. I would take agm over both trinkets, even the returning champion with its 10% heal, because 15s isn't long enough and heals are CHEAP. I'd rather increase my hp cap PERMANENTLY.
To elaborate a bit further since this thread has popped up again...
* AGM gives 40 HP more than one of the 7stam options. That isn't a lot of health.
* AGM's cooldown is 15 minutes. That means once per game.
* AGM's ~160 HP bubble is about the same as Defending Champion's HP on-use for a 1600 HP toon. Its not that different than the Mark of Tyranny at ~150HP. But...AGM has a 15 min cooldown, while the other two trinkets have 2 min cooldowns.
* The increased max HP from Defending Champ and Mark of Tyranny is really useful when getting focused. It makes you that much harder to kill and also gives your healers more time to actually get a heal onto you. The fact that the buff only lasts for 15s is mostly irrelevant - its for preventing your death during a big burst.
* Returning Champion has a heal for about the same as AGM (assuming 1600HP twink) - but again, on only a 2 min cooldown. It also is increased by verse, where AGM is not affected by verse.
* While AGM might give the most "primary stat" - that metric isn't really helpful or useful. We care about the exact stats it gives. 7 stam is NOT the same as 7 int or str or agi even though they are the same amount of "primary stats".
* Damage dealers are going to prefer damage options for trinkets. Either int or the champion trinkets for verse or a brewfest option.
Not quite relevant to this F2P discussion, but useful to note for any 19s or vets reading...
* For 19s, Insignia is an option because they don't have the first PvP talent. So insignia is a 2 min cooldown trinket instead of the 3 minute medallion. For 20s, this can be ignored.
* Theres a 9stam heirloom for vets, but again - this can be ignored for f2p.
So the decision on whether or not you want to use AGM is you have it is going to be based largely on class/spec. Most casters would 100% prefer int or would trade 4 stam for 5 verse. Most physical damage dealers like rogue/hunter would also prefer the verse. Most of those classes also have Brewfest options they would prefer.
So lets move to the ones would might prefer it. In my mind, Resto FC druids and melee classes like warrior/pally. However the verse from the champion trinkets is going to increase damage, self heal, and reduce incoming damage - especially since it works with stam. The more stam you have, the better verse is (and vice versa). So that will depend partly on what your other gear is. But the big thing is the big whopping 15 min cooldown. You can use it once per game - instead of every 2 mins or so whenever you get focused. When the AGM active is ready though, its definitely a solid option. But as soon as its used and you're out of combat - you're better off swapping to something else.