The manufacturing quality of the 721 is impressive. The thing that I really like is how versatile it is despite a very simple and easy to use design. Theres just one button on this and no screen at all, yet there are 8 different temperature presets you can access.
The way it works is intuitive too. 5 clicks turn it on, while 2 clicks move up through the temperature options. The temperature is indicated by the color of the light on top of the unit. There are 4 base levels, but you can activate a boost mode by pressing and holding the button for a couple seconds.
The only thing I would change about its design is the plastic swivel mouthpiece. It seems to be the weakest link, although it has performed as intended and doesnt impact the flavor at all.
The Pax 3 is also built well for the most part. The design is extremely simple and only has a single button, just like the 721. The button is hidden on the top of the unit, so it has a perfectly smooth exterior that looks very slick. The one problem I have with the exterior is how easily it scratches. It seems like every time I use it I manage to put another mark on it.
Related to the scratches, I cant help feeling like this is a vape I have to be gentle with. It doesnt give me the same feeling of durability that I get when holding the 721. In other words, Id bet on the Pax 3 breaking earlier from a fall or accident of some sort. Of course, I could be completely wrong about that.
While I think the 721 is built better overall, the Pax 3 gets bonus points for how elegant it looks and of course its bluetooth integration, which most people will probably not use.