I started a year ago with an eGo-c, and just like you, was quite satisfied with the vape.
Got into a co-op and lavatube. (now have many more vv devices) and, like you, I am finding that overall, my sweet spot is a 1.8 to 2.0 ohm coil with the Vivi at 3.7 volts!
Thing is, as others are...