Vox is everything that Alastor isn’t.
This may be a hot take but Vox is better than Alastor.
Vox fits the role of the strongest more so than Alastor does. Vox built all of his power from the ground up and was considered an equal by Alastor before he ever even formed the Vees, he’s gained the most successful empire hell and became a bigger influential figure than Alastor, Charlie and even Lucifer, he was so easily able to rally every sinner in hell to fight for him with or without his hypnotic abilities, and made all of heaven shit bricks, and to top it all off even tho Alastor mocked him for this, he has allies (who are despicable overlords) that actually care about him, meanwhile Alastor ironically doesn’t have anyone who truly gives a shit about him other than Niffty. Vox is essentially the real strongest sinner aswell the symbol of everything Alastor claims to be and ironically used to view Alastor otherwise.
Alastor on the other hand nothing of his is actually his. All of his power comes from a deal he made before he got to hell, and the reason he’s free from that deal is because of others he made to break out, were it not for all of that he would be nothing, just an ordinary sinner like the ones he torments, the way he died in life was anticlimactic for whoever he was feeling like when he made that deal, he lost the majority of his powers because he decided to engage in a 1v1 with an archangel with no angelic weapons and fled like a coward after getting embarrassed, this shows that the moment his back is against the wall he’s quick to run away and abandon everyone depending on him. These are all traits that show Alastor be a fraudulent manipulator, but this also makes him fit the role of a demon more than anyone, and that’s because of his trickery, cheating and snake like nature.
As much as Alastor mocks Vox for being powerless without the help of others, it’s just a projection from him as he’d be even less than nothing without outside help, it’s just he’s less obvious with it than Vox is.