Time to jump on the bandwagon. Here's the standard I'll be using:
S: Possibly broken.
A: Rarely skippable.
B: Good but sometimes skippable.
C: Okay.
D: Weak/niche.
F: Nearly useless.
Base:
S: Chapel
A: Witch, Artisan, Laboratory, Sentry,
B: Village, Militia, Throne Room, Smithy, Moneylender
C: Council Room, Festival, Merchant, Poacher, Cellar, Market, Vassal
D: Remodel, Bandit, Library, Gardens, Mine, Harbinger, Workshop, Moat
F: Bureaucrat