How is my Servant's roster?

The Servants that I have:

-Max Leveled (Respective Max Level): Okita, Tamamo Lancer, Lancelot, Siegfried, Emiya Archer, Chloe, Jeanne Lily, Ridertoki, Santa Salter, Euryale, Robinhood, Heracles, Spartacus, Arash, Hans, Emiya Assassin, Assassin Shiki, Serenity, Scathach Assassin, Mozart, Medea, Cu Chulainn and Mash.

-Not Max Leveled(Under level 50, mostly under level 20): Caesar, Elizabeth, Carmilla, Saber Lily, Ushiwakamaru, Kiyohime, Medusa, D'eon, Cu Chulainn Caster, Nobunaga(didn't have the remaining Golden Skull), Kojiro, Romulus, Darius and Cu Chulainn Prototype.

-Level 1 Servant: Brave Liz, Bedivere, Fergus, Saber Gilles, Tawara, Billy the Kid, Kid Gil, David, Jaguar Warrior, Diarmuid, Hektor, Benkei, Anne & Mary, Alexander, Boudica, Black Beard, Georgious, Irisviel, Caster Liz, Geronimo, Babbage, Paracelsus, Mephistopheles, Shakespeare, Fuuma, Hundred Face, Jekyll and Hyde, Phantom of Opera, Samson, Matahari, Tamacat, Lu Bu, Eric Bloodaxe, Caligula, and Asterious

PS: What kind of Caster Servant that I should raise for farming? I'm seriously lacking a good offensive Caster.