510 universal power connector - so you're not paying a premium for batteries you can't replace at a local b&m or swap with freinds
nothing yucky in the airpath. the universal vaporizer due diligence. I like glass and food-grade stainless steel. Some people are also comfortable with chromed brass, silicone, delrin, and teflon.
massive, absorbent, clean tasting wick. The wick makes or breaks the micro-skillet experience. Users who can't get huge rips off their wick resort to laying a glob on the coil and lighting it up. Blazing concentrate off the coil is a very different experience than vaping off the wick. I like braided and porous ceramic wicks, and some people are comfortable with silica. Seriously, a tiny shitty wick makes for a tiny shitty vape hit.
easy to clean. I'm partial to the ceramic cup in a metal shell concept. to me, its alot like comparing deglazing a stainless-steel pan vs an enameled cast iron pan. I'm talking about that browned food bits after you're done cooking dinner, and you splash a lil' wine on the pan to make a sauce. Much easier on the enameled pan, right? The whole atomizer unit should be able to come apart and be put back together, so you can give it an isobath.
rebuildable. you'll eventually blow a coil, especially those lightweight coils suitable for Ego batteries. a vape pen gets expensive if its too difficult to rebuilt, or the seals wear out after just a few rebuilds.
value. I don't think users should pay a premium for rebranded e-cig hardware. the batteries are commodity items these days, and all the innovation should go to towards the stuff attached to the battery. BYOB: These atomizers should be sold a la carte so we can Bring Your Own Battery
I will not endorse any vape pen on the market, but some pens are better than others. The trend in this is battery power and price. The units on the market that use smaller inexpensive batteries come with lightweight coils and thin wicks. Technology (and money) can help - some batteries are beefier than similar-sized batteries, some wicks hold more oil than similar-sized wicks.