If you're playing Cornucopia, then everything is automatically edge cased. Type distinction doesn't even factor in here.
If we're going to bend the rules and say that anything is allowed to be better than anything else, then Silver Surfer is better than Silver and it's also better than Peddler. Yes, Counterfeit and Graverobber are things, but those are two edge cases - one where Silver Surfer has the same type as the card being compared, and another with different type.
There are edge cases for everything. The card type isn't the why there is or isn't.
Perhaps I am misusing strictly better and I need to correct my definition, but to me it means better in all situations (Cornucopia not excluded).
I do not agree that Ruins/Curse/Copper are exempt from "strictly better"-ness, but I don't think it is worth arguing further about "Really bad card ideas"
If I am incorrect about what strictly better means to the forum at large I will modify my usage.
There are always edge cases though. Suppose we have similar cards A and B, where A is better than B. But is A strictly better than B? Some universal edge cases include:
- Possession, which makes you prefer B for any hand where you get possessed.
- Menagerie and Horn of Plenty, which may make you prefer B if you already have an A in hand.
- Masquerade and Ambassador, where you may prefer having B to give away instead of A.
So the definition needs to omit those considerations, at least. Some other things tend to be omitted as well. For example, we would usually consider "+4 cards" to be a strictly superior effect compared to "+3 cards", even though the latter may be preferable for reshuffle considerations.