At least she has good developed reasons for her embrace of the Light and subsequent conversion of her Blood Knights from ruthless to more Paladin-y.
Although the siphoning of a Naaru was a great theme.
On topic though, Alleria wins no contest.
All other power checks are pointless. Alleria's power are as high as allowed by the writers much like anyone else, but Alleria gets beaten by the champion of Azeroth, as much powered up from Ashjra'kamas and the Heart, in the hour of victory for the Void, so there's that.
All the mumblings about Alleria possibly joining the Horde, although a fun thought experiment, have literally no basis of existance. Alleria breeds a deep hatred for the Orcs, I just don't see how she could join a faction founded by one who she cannot talk with, and even then it would take years for her to mend her wounds despite spending a thousand waging a cosmic war and assumedly having time for introspection.