It depends on your battery, really... If you are using a 3.7V battery, non variable voltage or variable wattage, then Ohm's Law determines the Wattage and Amps used. A lower resistance coil gives you higher Wattage, which tends to give more vapor, compared to a higher resistance coil. Lower the resistance, the higher the Wattage, given the same Voltage applied.... although most batteries can't handle resistance below 1.2 Ohms without damage.
When using a variable voltage battery like a Spinner or Twist... or a VV/VW MOD like the MVP 2.0, higher resistance coils make little difference, except they wear down the battery slightly faster, because they require more Amperage to produce higher Wattage.
Most of us use 1.5-1.8 Ohm coils with our eGo-style batteries... some may choose higher... it's a personal preference
That's it in a nutshell