Certainly AA alkalines primaries (like Duracell and Energizer standard batteries) have to be the most common battery format. For rechargeables, I'd have to say AA NiMH cells are by far the most common for electronics that take easily replaceable batteries, such as flashlights, radios, toys, etc. 18650s or 14500s lithium ion just are not ready for the mass consumer, they're too dangerous unless properly managed solely by a device specifically designed for them and not easily replaceable (such as in a laptop battery).
Proprietary lithium ion batteries (not easily replaceable) have to be pretty common. They're used in all your other gadgets, like smart phones, tablets, mp3 players, cameras, etc. But I wouldn't consider them in the same category as flashlight batteries, because they're designed for a specific product and controlled by that product, which reduces their danger.