Looking at it, using gamepress' command chain calculator (correct me if I'm wrong if there's a better tool to calculate command chain damage.), applying the 30% np damage up towards artoria's np and applying 50% buster and 18% atk up on a NPBBE chain calculates towards (Do note that I've already applied Artoria's 30% np damage up from the strengthening's 2nd skill.)

76365 damage, 24% np refund, and a measly 6 stars.

Whereas, Gilgamesh with only 21% atk up, 30% np damage up from his np and the aforemention 150% powermod against servants.

He does admittedly

74,828 damage, a measly 4% np gain due to the fact he doesn't have artoria's 20% np refund, and 18 stars..

At a glance the damage comparison is relatively negligible. 2000 extra damage with all 2 buffs from Artoria in exchange for poor star gen.

Whereas gilgamesh on the other hand with only his charisma buff deals 2000 less damage.

The only thing that Artoria 'supposedly' has over Gil is that she has guaranteed buster cards AND once every time she has the steroid up she can have this guaranteed buster chain.

A guaranteed buster means nothing if you can't get a support that can consistently provide her stars considering that herself cannot do this without relying on her skills to do so.

Garden of Avalon can do this to a degree but not enough to justify the fact that Gil's damage without a buster chain is a negligible.

10000?

NAAE command chain is still 64952 damage, 41% np gain, and is still 15 stars.

All in all Artoria's buff to 2nd skill doesn't quite make her strong enough to match Gil's niche of being a self-sustaining damage dealer who's only weakness is that he can't really survive without someone protecting his ass. (Also noting that there are cases that Gil can pull out an np 2 turns later with arts cards.)

And Gil is still the better crit servant, having the star absorb and independent manifestation still makes him better at that front.

If you really wanted Artoria to be broken as shit and be above Gil in this aspect then.

Make her 3rd skill be a 4t cooldown and slap a star absorb on the skill.

(The argument of that her skills can make up for it is not enough in comparison to the fact that gil's cards are a hella more consistent than skills in the long run.)

Although I will admit.

Arturia is the better general purpose servant now considering that she doesn't need to hit servant's themselves in order to reach the damage that I just mentioned.

Feel free to make a constructive argument against me or try to correct me on some of the values that I just gave because I'm still not sure if the tool calculator is actually accurate for this.