The iTaste VV 3.0 is both variable watts (VW) and variable volts (VV). The Twists only have variable voltage (VV) and have no screen readout. With VV you do the oHms math, with VW the
device does the math if you use different
juice delivery devices with different oHms.
The iTaste VV 3.0 has a screen readout that will display puffs, remaining battery voltage, the oHms of the attached
juice delivery device and either the watts or volts you are currently using. The Twist has no display.
I have both Twists and iTaste VV 3.0s. I much prefer the iTaste VV 3.0s because of the display and I find it irritating to do the oHms math for the Twists.
Disposable clearos will severely limit your choices. All of them are plastic and can not be used with
juice flavors that crack polycarbonate tanks. You can get clearos with replaceable heads instead if you don't want to bother with cleaning them. It's dead simple to simply unscrew the head and screw a new one one.
The Kanger mini Pro Tank is a good choice for either a Twist or iTaste VV 3.0. It has a glass tank that will allow you to use tank-cracking flavors.