I use 3.0 ohm on 5 volts exclusively. Love regular Royal Smoker or Bauway brand CE2's and GotVapes Vision Extremes. I tried the Fluxomiser brand in XL size and wasn't impressed. I find they don't wick as good as they should. I'll probably buy some regular size Fluxomizers to try because frankly, CE2's are drying up. The regular sizes are next to impossible to find in Royal Smoker or Bauway. The Vision Extremes have no wicking problems. I just had one Vision Extreme die on me after two months.
Looks like they have them here~> Cartomizers and you can pick 2.4 or 2.8 ohm's..my guess is the 2.8's are probably the 3ohm ones as they usually are sold in ohm ranges..like mine are 2.4-2.6 I got from madvapes..also they look reasonably priced