The e-liquid with a 70/30 base (widely used) is compatible with all systems thanks to its fluidity. This mix puts above all on the restitution of flavours, while offering a rounder rendering and a little more consistent vapour.
An e-liquid is mainly composed of Propylene Glycol (PG) and Vegetable Glycerin (VG), two ingredients useful for the production of steam. We speak of a PG / VG mix to characterize this base.
The PG can be considered as a flavour enhancer, unlike the VG which will tend to stifle the aromas a little but produce more vapour.