I’ve always used butter, mainly because the idea of heating/cooking mayo weirds me out even though I know rationally that it’s a perfectly valid thing to do. (Probably something to do with how it goes all translucent and gross if you leave it to dry out, whereas butter stays palatable.)

I haven’t used margarine since I moved out of my parents’ house. Baby boomers might be into that fake shit, but I’m not.