wich servant needs to be added to the list ?

Summer Nero
Summer Raikou
Munenori Yagyu
Ereshkigal

Those are widely considered great new servants.

There are the summer servants, the best of which are:
- Caster Nero: best farming caster in the game, very good kit, and one of the very few buster casters.
- Lancer Raikou: One of the best ST lancers, SSR-level. Buster-crit oriented skills that go well with Merlin.

Other than that, MHX alter is the best quick berserker and will become a monster when Skadi drops, Meltlilith is a great quick servant, alter ego, arguably the best one offensively, Passionlip on the same banner is one of the best tanks in the game, and Waver will have (I think) a solo rate-up during valentine's if you don't have him.