"Categorically better"?
Proposed requirements for Card A to be categorically better than Card B:
1. Everything Card B does that is usually good is also done by Card A.
2. Everything Card A does that is usually bad is also done by Card B.
3. Card A does at least one usually good thing that Card B doesn't OR Card B does at least one usually bad thing that Card A doesn't.
Note that this would require determining which abilities are "usually good," which are "usually bad," and which are "situationally good or bad," which would also depend on the purpose of the card in question (e.g., mandatory trashing is more likely to be "usually good" on a trasher and "situationally good or bad" on a card that provides large non-trashing benefits). For example, is Nomad Camp's topdecking "usually good" (making it categorically better than Woodcutter) or is it "situationally good or bad"?
Of course, optional abilities are always "usually good," since if they're bad you just don't use them (edge case that's basically irrelevant in practice: choosing not to use it lets your opponent know you didn't want to use it). In fact, optionality can be a "usually good" ability in its own right: for example, 2nd Edition Throne Room is categorically better than 1st Edition Throne Room because it has the optional ability to do nothing instead of playing a card (though it's arguably not strictly better due to edge cases where you want to Throne an action but you don't want your opponent to know you wanted to Throne it and would rather your opponent assume you were Throning it against your will).