Aero versus Marks & Spencer's bubbly chocolate bars.

Both offer negligible cocoa contents; I would guess about 22% from the taste.
M&S's creation has, however, a certain advantage over Aero in the fact that it contains tiny malty crunchy bits.
On the other hand, there is far more to eat in an Aero bar.

My little cholesterol-smothered heart sinks at the thought that cocoa trees are slowly dying from some terrible cocoa tree disease, and that sooner or later chocolate will become a luxury, then a rarity, then a thing of the past. We'll have more and more substitutes, and that will be a sad, sad thing. Some years ago Britain already tried -unsuccessfully- to lobby the European Parliament into lowering the minimum cocoa contents in milk chocolate. Wrapped up Crap! Death by Cadburys! Mediocrity Bars! Just as well some of us have standards.