What is the best atomizer for you ?
Really not enough info. If you mean a clearomizer/
tank for a mod, then GS Air M or
tank are good. If you mean for an eGo style device, none better than Kanger T3S, although there are a lot of good choices for both - those are what I use.
If you mean what ohms 1.8, 2.2, 2.6 etc. then that is better determined by the flavor you're
vaping. Strong flavors need more heat - 1.5-1.8 ohms, lighter flavors need less 2.2-2.6 ohms BUT if you're using a variable wattage device, that isn't as crucial - just set the wattage to where it tastes best.