Ok, technically what I said about Thunder is false. Cyclops has a rather strong party-wide regen skill. The catch is, that same skill also applies that particular buff that raises burst gauge in return for eating 5% of one's max hp. So if you're shooting for over 15k HP, the regen loses to the buff's DoT component.
And I'm not gonna bother accounting for the +recovery buff in Union events. That requires convincing your union to dedicate up to 100 out of 400 available grails for one specific person's build. That'll be a hard sell for larger unions.