I did some testing to confirm this and realized something: the guild reputation you get at your first win without an emissary flag is the same for both factions (roughly 16 degrees of a circle), but when you add an emissary flag to the mix (guild one in this case), the guild reputation for winning as servants goes much higher:
![Servant win at streak 2 with a Guild Emissary Flag at level 5]()
![Guardian win at streak 2 with a Guild Emissary Flag at level 5]()
imgur album
With a guild emissary flag at level 5, winning a 2 streak as servant (from 1 win to 2 wins) gives me roughly 40~ degrees of experience, while winning as a guardian in the same conditions gives me roughly 20~ degrees of a circle of experience.
The disparity seems to come from the flag multiplier, not the base values, or maybe it's tied to streak (servants get more for higher streaks?). Whatever may be causing this, it should not remain as it is and both factions should level up your guild the same.