Variable voltage is a good place to start if you are committed to e-cigs. Most people start with something that is inexpensive but durable enough to use as a back up if/when they move on. Provari is an excellent quality with the downside that it only variable voltage vs. other choices that are both variable voltage and variable wattage. Personally that does not bother me as both get to the same place, with variable wattage being a little less fiddle as it is somewhat set and forget. If you think small is better look at the Innokin ITaste vv/VW 3.0. The battery will last 3 to 5 hours depending on how heavy you vape. The Innokin MVP 2.0 also seems to be a popular choice with a battery that people claim lasts more than a day. Both are non replaceable battery models. Moving to replaceable battery models, look at the VAMO or Lava Tube. I would recommend looking for something that will also read the resistance of your attached atomizer or other devise as it will come in handy for estimating proper voltage and later to measure coils if you chose to build you own. If your into all the bells and whistles, then the Evic should probably be on your short list, although it is somewhat delicate as mentioned above. Keep in mind if you buy a devise with replaceable batteries, you will need multiple batteries and a charger.