Compounding because of the incredible amounts of power it gives. I actually have a theory that an iron compounder could create a black hole.
Allomancy is very powerful, feruchemy is most useful and hemalurgy is not too evil E.g. dying mistings could give their steel burning to blind people so they can see.
Pancakes, that El is Elend, can't remember exactly what it is but 'there's many a man who has regretted not giving it another shake..., I don't play either but I do read. A lot.
The Iron compounder, if given enough time and Iron, could draw on all their weight and collapsw themselves into a black hole if they exist in the Cosmere, I think