I thought the whole point of mayonnaise was olive oil, it what gives it the peppery edge. Making it will other oil seems pointless, but then the point of industrial mayonnaise seems to provide a substrate that holds the rest of the sandwich together, rather than edibility. I don't mind the real stuff, but other mayonnaises can fuck off, it's just oily goo, like they harvested the various exudates of greasy teenagers.
Salad cream though, that's where it at. You want haute cuisine, the kind that kicks a garcon in the balls, then two slices of thin sliced bread, a pack a ready salted crisps, and a bottle of salad cream is all you need.