Team building

Hi! Since i didn't find anything good in the "merlin rolls" (rng is against me so i'm trying to make a team with heracles that i got clearing cache when i started the game) i'm asking wich is the best gssr banner to pick based on my servants:
(I have some 4 stars and spared 3-2-1 star/s)

4*servants:
Heracles
Martha rider
Nursery rhyme
Jeanne alter santa lily
Stheno

I guess i should aim for the caster banner, but maybe there is a banner that fits better with heracles
Thanks for the help and happy Holidays ^^