blood of the ancients vs bone of the ancients

[TEITANBLOOD]

which one should i use with zero?

[Diogenes49]

breath of the Swraphs

[Nakos]

Personally, I prefer a Corrosive Bone, but a Breath of the Seraphs would be great if you had one.

But .. I prefer Maya to Zer0, so that impacts my perceptions too.

[Elikir]

Blood of the ancients : its HP regen is too weak to truly matters during fights, you're much better off using either a transfusion grenade or a moxxi weapon like Rubi or Grog Nuzzle

The HP boost is fine, and i can see the idea of making Zero "%HP based heal" better, but remember there is a mechanic called "health gating" which basically prevent you from dying for few second when you should have been dead from 50% +2 flat HP to zero

There is actually a tactic which consist of reducing your max health to abuse that mechanic while also having it low enough to regen it with only one shot of moxxi weapon/transfusion tendrils/child grenade, so you're juggling between health gating triggers

Which means making your max health bigger make such tactics harder to pull off, also more health to regen between fights, you're better off using a skin of the ancient or resist relics, as it upgrade your damage resist and/or upgrade your shields capacity/recharge rate (shield recharge naturally and faster than health, and after fight for your life, shield regen to max each time, so having more can help staying a live between downs)

Bone of the ancients : Contrary to most damage bonuses, elemental ones are multiplicative, shock is universally fine to use (aka only very special enemies resist it)

The cooldown rate can also help a bit to both your survival and your damage output, as you can use deception and passives related to it more often ( 6 sec timeout from damage, perfect to let shield recharge, get better position either for headshots or safety, more uses of innervate+death blossom etc)