Antidas had the war all but won through skill and/or luck. If Meru hadn't betrayed him at the decisive moment, it would already be over. Paullus and Gaellius don't even try to win. Whatever the basis for his belief, at least Antidas wants to restore the empire.
Antidas's character is well illustrated by his relationships with Feng and Deliar. It's possible for a fraud like Feng to fool Antidas for a little while, but Antidas is smart enough to listen to Deliar's opinion about Feng in the end. That's the behavior of a leader capable of recognizing his own failings and capable of recognizing a loyal counselor who gives good advice. Paullus doesn't take anyone else's advice, not even from a loyal subordinate like Carbo. Furthermore, there's nothing in the game to indicate that Antidas is miserly, or vindictive, or crazed. He may be arrogant and susceptible to flattery, but he's not inherently nasty, paranoid, or unhinged.
Antidas also has legitimacy. Without any legitimacy Paullus can only rule through brute force. Gaellius doesn't have nearly enough legitimacy, which is one of the reasons the nobles in Maadoran are all plotting to undermine his authority. The Aurelians are conniving upstarts. I agree completely with Lord Senna's opinion of Gaellius: even though Gaellius already has more soldiers than Antidas and Meru combined, he still wants to invite the Ordu into Maadoran. Gaellius doesn't care what form the world takes as long as he's got the biggest slice. No wonder he tries to suppress all the old knowledge; it could be a threat to his position.
At worst, Antidas is no worse than any of the other potential rulers. There's no justification for the way the game's editorial voice insults him at every opportunity. That's probably the main reason I'm sympathetic to him, actually.