Have both Sanzang and Illya, the former at bond7 and the latter close to bond7, but both are unfortunately just NP1.
Other relevant servants which i hv for Berbatos include Jalter (Np1, Bond5), Herc (Np5, bond 10), Raikou (Np2, bond 10) , Martha (Np2, bond 6), Nightingale (NP2, bond 6)
Given the above, which Caster is a better choice for this raid?
Take my answer with a grain of salt, but I'm pretty sure np5 bond 10 herc would outdamage both your casters. Out of illya and Sanzsmg though, Illya has more one time burst damage, so if you intend to make it as quick as possible she's probably the better choice.
Isn't NP5 B10 Herc superior by far? (Not sure since I didn't do the math)
Anyways, for casters I would recommend Sanzang so that you can
1. Take a Merlin instead of a Waver as support. ´
2. Take a CE without Starting NP such as Black Grail with you.
As far as I know every caster is out damaged by Berserkers even on assassin targets due mostly to better stats and the damage modifier.
