Of the new servants, Drake is notable as the first 5* Rider and a strong, independent servant at that. With her strong star gen and fantastic NP gain, Drake is one of the best Riders in the game for a long time.

Anne Bonny and Mary Read have a powerful critical damage-oriented skill set with a powerful NP which only grows stronger as their HP reaches critical levels. However, they require extensive ally support to provide critical stars in order to put their skills to use, and until certain CE's and servants come out their NP's secondary effect is difficult to consistently utilize properly. Fun to use, but not as effective as you'd think in action.

Euryale is very strong against males, and a fully levelled NP5 Euryale is one of the possible keystones to beating a certain stage in Camelot.

Medea (Lily) is the premier healing unit in the game, with the overall strongest heals, in addition to a cleanse on her NP. Her High Speed Divine Incantation allows for on-demand NP Heals. She is pretty good for hard stall content where the enemy will debuff you often (i.e. Nerofest Redux 1).

Hektor has a powerful stun skill and relatively high and consistent damage from his AOE NP, but he's fairly average in all other aspects. He has his uses over competitors like the two Cu's and Romulus, but in most scenarios he's a bit outclassed.

David is famous for his team wide on-demand dodge with Harp of Healing. He is a very strong utility servant, and also very accessible. In fact, he will join you after the completion of the singularity! Perhaps he feels strong sentiments towards the Chaldea crew?