it's just flavor and taste. Really it all comes down to power over the coil. you could vape at higher voltages but with a higher ohm resistance have a lower power than a 3.7 with a low resistance atty.
check out ohms law. A lot that comes through is going to be battery cost and mah per battery.
Theres a lot of differences in battery and combos, also two brands may not be the same, i have the same 16340's in ultrafire, trustfire and lifepo that should all be the same, but they swing .04v variances and some drop off sooner than others.