I haven’t played it personally, but Savage Attacker was garbage in 2014 rules, and 2024 didn’t change it any, so arguably it’s even more garbage now due to power creep. Great Weapon Fighting (GWF), to my amazement, has actually gotten literally worse not even accounting for power creep. It’s still better than Savage Attacker once you get a second attack though, due to Savage Attacker’s once per turn limitation. And yes, the raised damage floor from GWF does seem to mean less situations where you would want to use Savage Attacker, and lowered gains from using it.

As for how much it’s affected, assuming your DM does not allow these feats to apply to Divine Favor (not sure how the 2024 rules feel about this but I believe that was considered the ‘official’ ruling in 2014), Savage Attacker adds 1.37 average damage to a hit with your maul when you do not have GWF, but only 0.91 average damage to a hit when you do have GWF.
Source: calculated by myself with anydice

P.S. As a fellow maul enjoyer, thank you for your dedication to the superior 2d6 weapon.

Divine favor says that the extra damage is ‘weapon damage’. So I think it works with savage attacker and gwf (dm agrees). I know normally gwf is considered ‘bad’; but I think with the 3 dice it’s pretty ok for me. But it stinks that savage attacker gets even worse with gwf; especially given that it’s an origin feat.

My goal with the build is to find ways to get my maul to do as much damage as possible (I’m planning on great weapon master at level 4). But savage attacker really seems to be useless. I redid your calculation with divine favor, and it looks like savage attacker would only be adding .95 damage:

Divine favor added in

The origin feats are supposed to be less powerful because they are the ones that are available from level 1. I personally think the savage attacker origin feat is one of the weaker origin feats, but it is also the only one that will directly increase your damage output. So if you’re only looking to increase your damage, it is still the best choice.

Savage attacker is mathematically most powerful on 1d12 weapons and way less so on 2d6. So if you are commited to only using the maul you will feel it’s effect way less. But a lot can happen in a campaign, maybe you’ll find a cool magical Warhammer or greataxe that you can use. Even if they’re not magical, having two different weapon masteries that you can strategically use in different circumstances is really good.

That’s true! With a great axe; savage attacker is pretty ok. I just wish the feat was more universally applicable. It also conflicts with gwf; because gwf is better with allot of small dice, while savage attacker is better with fewer large dice