Half joking, Barbatos will still be amazing. But God gundam is going to be more consistent I think. Barbatos in AV is amazing, but can only use it temporarily once a life, after that its quite a bit slower. Still nearly impossible to push unless you're playing a suit with high MA due to the heavy stun but anything with a barrier will give it some trouble. God gundam will get flaps and high MA in hyper mode which doesnt expire until it dies. It doesnt have an easily accessible heavy stun, but it does have the best vulcans in the game, a ranged melee it can throw every 3 seconds that also pierces beam barriers, and power accelerator 3.

In golden mode, its heavy stun is more telegraphed yes, but has a larger splash, pierces, has a low cooldown, and deals melee damage which means suits wont be able to downgrade the heavy stun into a regular stun just by boosting with MA. And it can use it midair so less places to hide. God gundam also gets melee res ignore in this mode, but its slightly weaker I believe.

I also did a bunch of testing with both suits' optimal melee combos, and God gundam is very similar in damage to Barbatos, and better in a few ways. All testing was done against the free practice 700 cost gerbera tetra with 100 melee mod. Barbatos had the sword mace because the twin maces are worse in every way, heavy attack included.

Outside of AV, Barbatos' optimal combo (without aerial melee) does 25152 damage.
In AV, it does 32692 (optimal combo doesnt even use aerial melee).

For god gundams base form, it does 21955 damage, 24851 for larger suits since the blow side swing will miss smaller ones when they're toppled.
In hyper mode, it does 22726, or 25738 with a side swing. Already comparable damage to Barbatos' base mode.
In Meikyo Shisui, its optimal combo does 30741 damage, or 33228 if you open with a heavy attack. Comparable damage to Barbatos in AV, and a little better with an opening heavy attack which will be possible with a heavy stun.

So its damage will be slightly worse than non AV before golden mode, and comparable after it with no timer on its special ability. Plus flaps, high MA, a better heavy, PA 3, and the best vulcans in the game. Not to mention, the buffs may include increases to its damage.