You'll see puff counts thrown around like they're the only spec that matters. But a 25,000-puff count is meaningless if the battery dies at 5,000. Look for devices that match their puff count with an adequate battery. The VERTEX-25K, for instance, is designed to actually reach its claimed count.

Don't be fooled by marketing. A device that honestly delivers 15,000 puffs is better than one that claims 20,000 but falls short.