What should I upgrade first?

[Katya]

the nautilus holds more liquid but the gs air is a way better tank i actually hate my nautilus i only put in on for the picture.

The GS Air M holds 4 ml; the GS Tank--3 ml.

 

[chellie]

You may need it not only as a backup, but for sampling new e-juices. It's small and cleans up well. Just rinse the coil under running water and you're good. Or soak it in a bit of vodka for a few hours.

I used to use Evod glass tank with a ego type of battery - and then upgraded to a istick type of device and I still used the Evod with it and it was fine for me - I wasn't looking for huge clouds and truly felt that it was a good vape - and I still keep them around as a back-up and as mentioned when trying out new juices.