Caster (Circe) (Was trained by a god), Caster (Fate/stay night) (Was trained by Circe)
Reasoning is shot. Medea was considered by Roman as among the top 5 of magi in history. Considering he is Solomon, that says a lot. Circe is up there as she trained with Medea.
Archer (Arash) (Same as Tristan), Rider of Red (Achilles) (His skills were described as "exceedingly close to the gods"), Lancer (Hector) (Lost to Achilles due to a paper-thin difference in skill), Archer of Black (Chiron) (Nearly equals Achilles and trained him), Archer of Red (Atalanta) (A peer of Chiron with godly training)
No to Atalanta and maybe Chiron. Chiron admits that he's good at many things but he doesn't stand out. He's a jack of trades. And then, he shoots Atalanta's arrows out of the air, so much so that Atalanta has a one-sided rivalry with him.
Arash, is also so skilled that Chiron outright admitted inferiority and says that he's just a teacher, not a hero at the top of the summit. Also, he can replicate Atalanta's NP with a simple barrage, killing 10,000 people in one volley.
Lastly, Tristan's bow is enchanted so that it homes in. It's a compliment more to Arash than him for them to be compared.
Saber (Fate/stay night) (Is considered a top-class Saber), Saber (Bedivere) (Can fight alongside Arthur as a peer, despite being a mere human)
Arturia is top class less for skill and more for NP, good stats and ridiculous instinct. Bedivere is the most normal in the Round, and it was only in Camelot that he had enough oomph to his legend to be a heroic spirit.
D: False Caster (Says he has no actual battle experience, and merely writes about heroes)
E: Assassin (Mata Hari) (Calls herself useless in a fight, with no skills whatsoever), Caster (Fate/Extra CCC) (Same as Mata Hari)
I don't see the point of these.