For now I have en adv CoC Zoro in terms of Ap in similar lvl, Zoro Ap is really op and his higher end(strongest one) are easily around Low top tier, his best even mid top tier attack. So overall I see Zoro as low top tier, Luffy should be low top tier in G2/G3, with G4 he should be mid top tier and if we get a new form,I assume he is around mid top tier(higher stages) to high top tier(lower stage).
Current Luffy ~ Admiral lvl(counting a new form)
Current Zoro ~ Rayleigh lvl(low top tier).
Zoro is really op and for the reason Luffy top vize( Sanji will join when he learn adv CoC), but I have Luffy above, people will witness soon Luffy ap when he enter Boundman or his new form,you thought?