Efficient strength training tends to have a component of optimizing for stimulating the relevant muscle recruitment neurology.
I'm confused by your exclusion of some drugs - are there any which have not been bred or otherwise improved over time to maximize impact? Why is porn not included? I presume you'd exclude algorithmically-tuned-for-engagement social and mainstream media, but I don't understand the category you're looking for.
I'd also need you to specify "good/useful/advantageous TO WHOM?" clearly these are attractive enough for users to choose them, so from a revealed preference standpoint, that's valuable to them. More abstractly, escapism and comfort in a cruel world does seem to have some value to a "generic" human. It's probably valuable in some models of society to pacify the masses, who are contributing mostly existence and cheap labor. In the (ludicrous but common) model of everyone being equal and intellectually engaged in society, such things probably have no value.
Superstimuli in this case are things that are optimized towards stimulating some part of the human brain.
Things which are NOT superstimuli include: drugs which have not been synthesized or distilled for the purpose of enhancing their effects on a person, porn of real humans, etc.
This question is less about specific examples(although they may be useful for interpretation) and more about the general case of superstimuli as defined.