Welcome first time poster!!!! I think you have two of the best portable herb vaporizers, so things such as battery life or wonky look are a fact of life. But, are you looking to vape flowers with a pen? Dabbler is a wax pen, in a completely different ballgame as herb vaporizers. A direct comparison is hard to make for a couple reasons.
Wax pens like Dabbler are conduction vaporizers best for solids & oils only. They efficiently transmit heat directly into the oil, evaporating a tiny amount at at time. This allows the heaters and the batteries to be very small, hence the pen like size. Battery life is anywhere between a few days and a few weeks depending on use. Dabbler does well in this regard because the internal circuit reduces power draw and limits the temperature of the heater, extending the capacity and the lifetime significantly.
Last I checked, Thermovape is a true convection vaporizer / MF is partly convection. Convection vaporizers heat air that passes through the plant matter with little or no contact of the herbs against a hot surface. This is no small feat for a portable vaporizer, and partly why we never came up with a portable version of our box vaporizer. True convection vapes have to heat a large volume of air (about a liter per big hit) to high temperatures (more than 500°F in many cases). The air is transported into the herb chamber, losing much of its heat along the way. To get an acceptable hit, you need serious battery power. The result is a lovely taste though.
Some pen styles are supposed to work herb but I haven't tried one that doesn't char the herbs by direct contact with a hot surface. New stuff is coming out constantly from omicron/persei, so I would look there. As far as I know, no portable for herbs works without tinkering, practice and a bit of spending. Let me know if you find something good.
Quickly- about lithium battery life. These things are hard on lithium batteries: not charging them fully before first use, leaving them discharged for long periods, using them hard when fully charged (oddly), using them while they are hot, leaving them to charge for long periods on no-name or cheap brand chargers.