Let's see...
Chaos Tatsuya: low A to S, his power goes up based on how many foes he's fighting so it's not quite in stone.
Tatsuya Suou: A.
Homura Akemi: High B? A at most but high B now I'd say.
Kamen Rider Snipe: A in his highest forms. ones that matter.
Spiderman: High B with Iron-Spider suit, only a high C if forced to rely on powers and no tech.
Flynn of SMT 4: A.
Chie: B
Hilda of Stella Glow: A
Taylor Herbert: She controls bugs and has an acid hammer, no superhuman powers. D in theory.
Kamen Rider H2O: Currently a high C, but after getting all his forms will be B or possibly A.
Shiki Ryougi: A.
Harry Dresden: B, maybe lower end of A.
Naoya of Devil Survivor: A, maybe S if I really go over the top with how much a COMP can pull off.