26 Gauge is my favourite gauge to work with, and I tend to vape under 40W, usually under 30W. I use either Kanthal or SS 316L, with my SS builds being a bit lower in resistance.
I usually aim for about 0.7-0.8 for single coils with kanthal, duals usually turn out around 0.3 to 0.4 ish. 2MM ID I find is nice for lower wattage, and I find it really depends what tank I am using what I can run my coils at, something like a subtank needs about 18W and works nicely, a dual coil build in another tank like Crius or griffin between 32-40W usually is nice for me.
With SS I do quite a bit of variation in coil size, and generally use it in TC mode.
EDIT: I should add, I generally use RTA's for convenience and find many newer tanks to offer such great flavour I don't drip as often as I used too. Although any smaller, thinner ID coil, with wire that isn't too heavy a gauge will not need much power due to the surface area being heated, so a lower resistance build will need less power with 26G wire due to there being less wraps than say 24G.
