Voadam
Legend
5e angels are tied to good gods and 4e angels are tied to gods regardless of alignment, in other editions the ties to gods have varied dramatically.I don't think you can ask the same question though, because there is not a major third party of "extremely powerful good beings". The closest you can get are the Celestials, you could have "Sa'Dew, Archangel of Light and Healing" but the celestials and angels specifically serve the gods, so you'd expect this being to be a right-hand of the god/goddess of light and healing.
the Demon Lords and Archdevils don't serve the Evil Gods. In fact, they fight each other, and the evil gods have angels in some editions, and demons and devils in others, which is even MORE bizarre to have Devils who have sworn allegiance to Asmodeus serving Bane, God of Tyranny.
If we had a major good faction that wasn't associated with the Gods, it could make more sense, but since we don't, the incongruity of having two major evil factions plus the GOO is odd.
In 5e though in the MM there are the Modrons of Law and the Slaadi of Chaos who are big planar alignment factions not tied to gods which leaves the Angels as the big good faction being tied to gods of benevolence as are many of the other Celestials.