Both promise crispy results without deep frying, and both have genuinely loyal fans in their own right. But they're actually better suited to different kinds of cooking rather than being directly interchangeable, which is where most buying confusion comes from.
An air fryer uses rapid, concentrated hot air circulation in a compact chamber, which makes it fast and efficient for smaller batches. An OTG, or oven-toaster-griller, is more of a traditional oven in miniature — it heats a larger cavity more evenly, but it generally takes longer to get there.
Speed and convenience for single-serve to small-family portions is where the air fryer clearly pulls ahead — reheating leftovers, frozen snacks, quick weeknight cooking when you don't want to wait. Preheat time is minimal, and cleanup is typically a lot easier than it is with a full oven cavity.
Baking is the clear OTG advantage, and it isn't close. Cakes, larger batches of cookies, anything that needs to rise evenly across a bigger surface — an air fryer genuinely struggles with that in a way an OTG simply doesn't, because of how the heat is distributed.
If your cooking regularly spans both quick snacks and actual baking, the two appliances are genuinely complementary rather than redundant. A lot of households end up using both for different jobs entirely, rather than picking one and forcing it to do everything.
Choosing just one: go air fryer for quick, crispy, small-batch cooking, and OTG if baking is a real, regular part of your routine. If budget allows and you genuinely do both often, owning each solves a different problem well enough to justify the space.