It all has to do with how warm of a
vape you prefer. Generally, the warmer the vape the lower resistance you want.
This analogy really helped me understand. Let's say your stove is the PV. You have a pan (standard resistance) and a foam cup (low resistance) If you put water in the pan, and put it on the oven it is going to take longer for the water in the pan to heat up, than it would if you had the water in the foam cup.
I generally use low resistance cartomizers/atomizers because I like a warmer vape. If you need a more in depth explanation search this forum for "Ohm's Law"