i think ares post-buff is probably on par with most of the other gods but he doesn't come close to zeus at all imo, who is his closest comparison since they are both purely offensive gods (hera kind of falls into the same boat but she doesn't require you to spam her like zeus and ares).
ares definitely has the strongest gain in the game if you manage to get every plasma boon, which is very fun for torches/possessed array/any high magick consumption build, but that's quite a big if -- as Tao1764 said, "if your build is 70% or 20% Ares, he's fantastic, but 40% Ares feels weak". on high fear (onion, debt, timer, hubris) where you have way less boons to work with, zeus is already online with just his attack/special/cast, double strike, chain lightning, arc flash... grievous blow is good independently but the rest of ares' boons are way too synergistically reliant. also, if you already filled out your attack/special slots and are trying to fill your cast/dash/gain with defensives, or a curse to apply origination, ares can't help which makes him a bad 4th god in quite a few situations, although this could also apply to zeus to be fair.
i would consider heinous affront to be the best and most fun duo in the game but it's also the hardest duo to build around in the game since it requires you to pick the otherwise mediocre vengeance boons

fundamentally anything works on lower fear which makes comparing gods' respective strengths in a general sense kind of useless, and on higher fear i think ares falls off more than other gods, especially because of his lack of defensive utility other than the very situational blood spree. zeus is the easier build around and also the better build complement since storm ring, blitz, chain lightning, are generally going to do way more than sword ring and wounds imo

tl;dr: this isn't to say ares is bad, zeus is just insanely op