The critical factors of an ideal vaping experience will involve both the mechanical gear used to make the vapor and the e-liquid used to create a flavorful and volumeful amount of vapor that provides adequate throat hit.
E-Liquid:
Possibly the most critical factor, and possibly the most difficult to find. Most responsible factor for what can determine the Perfect Vape: flavor, throat hit, and vapor production.
Nicotine percentage is most responsible for the throat hit, but vapor temperature and a higher pg content also play a role. Vg percentage plays the most important part in vapor production. And Pg arguably plays the most important part in flavor. Finding flavors that the user will enjoy using on a consistant basis can be one of the most difficult for the new vapor to find, and even most experienced vapors are always on the lookout for a new flavor to add to their flavor rotation.
Juice Delivery Attachments:
Here's where there is the most variety in designs, and also critical. All involve some type of wicking system and a heating coil to vaporize the e-liquid into vapor.
The resistance (Ohm rating) of the heating coil can be another factor which can affect the vape experience. Low resistance can produce a warmer vape. Standard resistance can produce a cooler vape. With clearomizers, top coil can produce a warmer vape. Bottom coil can produce a cooler vape.
From drip atomizers, clearomizers, cartomizers, to RBA/RDA's (rebuildables); all differ in their form and function, and all will have their proponents in personal preference as to which provides an individual with what they feel provides them with the best vape experience.
Proper Terminology: A Primer on Juice Delivery Attachments
Batteries and the devices that use them:
Li-ion batteries, and the devices that use the energy from these batteries play an important part is supplying that energy to the heating coils in the juice delivery attachment. High quality Li-ion, Li-Mn, or hybrid batteries should be chosen for safety first (safe chemistry vs protected), and for either high battery capacity (ICR), "high-drain" ability (IMR), or a combination of those (hybrid).
Battery Basics for Mods: IMR or Protected?
Fixed voltage vs variable voltage. Using a mechanical mod you will be at the mercy of the battery and the resistance of the atomizer you choose. Since the battery drops in voltage as the battery is used, the vape quality will also decline from start to finish of a fully charged battery. Voltage regulation with a processor-based mod can keep the vape experience consistant and also allow the option of adjusting the voltage higher or lower to the benefit of the user.
Variable voltage is a very useful function which allows the user to make adjustments to fine tune the voltage output for individual flavors, much like a dimmer switch for a lightbulb. Few flavors taste their best at a single fixed voltage.
Finding Your Flavor's "Sweet Spot" Using Variable Voltage
Some variable voltage processors even differ in the way that they regulate higher voltage via PWM (pulse width modulation), differing in the frequency of the energy pulses. From the 33.3 hz of typical Chinese-made regulators ("rattlesnake effect") to the nearly flat-line 800 hz pulses of processors found in the Provari, iTaste MVP and VV, and DNA mods, some vapors can detect a difference in the vaping experience because of the PWM method used. This is a controversial subject which is popular to debate among enthusiasts:
http://www.e-cigarette-forum.com/forum/variable-voltage-apv-discussion/488840-rattlesnake-effect-why-cheapo-vv-exception-itaste-mvp-dont-vape-same-provari-dna20d.html
Provari vs Vamo on an Oscelloscope
There are those vapors who are totally devoted to the bottom feeder mods. Self-contained, simple-as-they-come battery devices that combine the full flavor of a drip atomizer with the convenience of a tank.