It will depend on your battery. The eGo type batteries are usually (correct me if I am wrong, folks) a 3.3 to 3.7. I use the 1.8 or 2.2
coils on these. I did buy some 1.5 ohm
coils but have no idea why now.

I have a variable volt pass through battery coming and will try the 1.5 on that battery when it comes. I just keep looking up the ohm/watt/volt recommendations when I need to know what to do. I get very confused sometimes, but that's ok. At least I stay in my comfort zone that way!