Both sides are at their peak and all major characters within their forces are present. They are being led by the Emperor of Man and Tiber Septim, respectively. Only restriction is that Tiber Septim does not get the Numidium for hopefully obvious reasons.
The Septim Empire has multiple interdimensional spacestations to explore the outer realms of Oblivion (such as the Battlespire), multiple dragons who do their bidding (including Nahfahlaar, who prevented an at least continent level explosion and withstood an island exploding at ground zero and survived*), the shadow legions and various artifacts (both legendary and enchanted equipment). Even regular non-magical soldiers can be superhuman (from stabbing into stone levels to taking out whole legions by themselves levels). As mentioned above, the Septim Empire has access to space travel and likely even have settlements on other plane(t)s (the Khajiit definately do).
However, I feel that the Imperium have far more numbers and superweapons, so it'll likely fall down to Tiber himself.
*Possibly way higher as Kaalgrontiid was going to use said power to become a moon/god.
Tiber talos would be the one carrying the team the living emp best is universal with the whole fighting chaos hours duel. Chim talos should be above that.