There are so many different vape pens on the market. I would first ask, what are you looking to achieve? Do you need pain relief or are you looking to stay lifted throughout your day?
The new hmblt dose pens have made a huge movement in the industry, as they are "dosed per inhale" and have options like "Bliss, Calm, Sleep, relief" (http://www.hmbldt.com/)
A lot of people love Bloom farms and Kurvana (http://kurebotanicals.com/) as they are very use to use depending on what you are looking for in your daily use: Sativa, Indica and Hybrid options.
I hope this was helpful!