Here is my take S/A/B/C/D/F:
Races
Chromatic: C
Metallic: B
Gem: C
Subclasses (as compared to other subclasses for that class)
Monk: Ascendant Dragon: A
Ranger: Drakewarden: C
Feats (with ASI being a B)
Gift of the Chromatic Dragon: D
Gift of the Gem Dragon: B
Gift of the Metallic Draggon: C
Spells:
Nathair's mischief: D
Rime's Binding Ice: A
Ashardalon's Stride: B (S for a Ranger or EK)
Raulothm's Psychic Lance: A
Summon Draconic Spirit: B
Fizban's Platinum Shield: D
Draconic Transformation: A
Of note I have not played these, so this is largely a guess based on the descriptions and analysis without any empirical data. It is possible Ashardalon's stride causes problems in play with damaging allies but on paper it looks managable.
Races
Chromatic: C
Metallic: B
Gem: C
Subclasses (as compared to other subclasses for that class)
Monk: Ascendant Dragon: A
Ranger: Drakewarden: C
Feats (with ASI being a B)
Gift of the Chromatic Dragon: D
Gift of the Gem Dragon: B
Gift of the Metallic Draggon: C
Spells:
Nathair's mischief: D
Rime's Binding Ice: A
Ashardalon's Stride: B (S for a Ranger or EK)
Raulothm's Psychic Lance: A
Summon Draconic Spirit: B
Fizban's Platinum Shield: D
Draconic Transformation: A
Of note I have not played these, so this is largely a guess based on the descriptions and analysis without any empirical data. It is possible Ashardalon's stride causes problems in play with damaging allies but on paper it looks managable.