I recommend using a cartomizer in a cartotank. You can easily see the juice levels in the tank, which is a reservoir of e-liquid that continuously refills the cartomizer each time you take a vape. The cartomizers used in a cartotank needs to have holes in them in order for the juice in the tank to be able to reach the inside of the cartomizer. These "pre-punched" cartomizers are available everywhere.
I use cartotanks exclusively because in my experience they provide me with the best flavor over string-wicked clearomizers or vivi nova tanks. It makes sense that this is so. The only thing bringing the juice to the heating coil in clearomizers and vivi novas are 2-4 skinny string wicks - that's a very small surface area to wick juice.
On the other hand, the heating coil in a cartomizer is totally surrounded by the polyfill - a marked increase in surface area. More juice to the heaing coil results in more flavor. An advantage that a cartotank has over a cartomizer used solo is that it keeps the polyfill wet, so that if it is set up properly there will be no dry hits.
It takes 5 minutes to set up a cartotank, 1 minute to refill it. Depending upon the size of the tank, it can last 1-3 days of carefree vaping.
View attachment 180033 A 2ml pyrex cartotank on an eGo battery.