User blog comment:J80Kar/UNSC vs The Holy Britannian Empire/@comment-379205-20120821043117

Overall, I give my edge to the UNSC. Mecha are horribly overrated as weapons platforms, mainly due to their nasty habit of being disabled after taking a tank shell to the leg. In truth, any legged form, particularly a humanoid version, is inferior to a tank. While I do not know much about the Code Geass universe, I would hazard a guess that UNSC's M6 pistol has greater stopping power with its large 12.7mm round, and the SMG and shotgun will prove a more useful combo than an SMG and flamethrower, as the flamethrower does not require the user to carry around a tank full of flammible gas. I'll also give the UNSC the edge in rifles, as BRs and ARs give them greater versatility, i.e. both a designated marksman weapon and standard AR. Finally, I doubt the Britannian Sniper rifle can stand up the sheer stopping power of the UNSC's 14.5mm discarding sabot-firing SRS-99. The UNSC's rocket takes as it is capable of firing guided missiles (seen in Halo 2 and Reach), and unguided rockets, and it has two barrels. Couple that with the more advanced armor of the Scorpion and the extraatmospheric capabilities, and (presumably) more advanced engines, missiles, cannon etc. of the Longsword. Finally, add in the final ace in the hole with the SPARTANS and their MJOLNIR armor. About the only thing the Holy Britannian Empire has going for it is the better gunship and the frames presumably being better armored than the hogs.

Overall, the UNSC wins this battle for their superior, more advanced technology, and their greater combat experience. From what little I know of Code Geass, the Britannains were fighting mostly resistance organizations and massacring civilians, while the UNSC took on the more advanced Covenant and the highly virulent Flood and managed to hold them off and even win against all odds (admittedly helped tremendously by internal conflicts within the Covenant and the exploits of one highly skilled supersoldier).