I got a chance to try out the turtle, centaur, and dragon banners for a bit during the stress test. In general, I like them, especially the turtle banner. However, I realized there is one aspect that none of the banners really addresses and that is conditions and debuffing. I propose there should be another banner that focuses on these aspects.
The new condi banner would readily apply some random conditions, perhaps among the list of weakness, poison, confusion, torment; nothing too OP (ie, not burning). It should also have a moderately long cooldown skill that can strip 1-3 boons to 10 enemy targets, perfect for softening up a group or countering turtle banners. For the allies, this banner should apply some boons, such as might, swiftness, regeneration, and resistance. While turtle banner can give resistance, this new banner should do so more readily. Finally, this new banner should also provide some AoE condi cleanse, perhaps 3 condis to 10 allies nearby on a relatively short cooldown. In terms of CC, maybe it can give some AoE slow or taunt.
Teams that rely on condition damage would want to take this to boost up their condi application and weaken their foes. Teams that expect to encounter heavy condi pressure will want to take this to have more active cleanses and resistance.
Just something to consider 