I've settled on two juices in my echo-e cartos and i've been using them as my all day vapes. The Prime 15 and the tiki
juice from Halo is what I use. I started using them in boge 2.0lr cartos and IMO the juice was very strong, flavor-wise. I switched both flavors over to the echo-e and it seemed to smooth out the flavors quite a bit and now they are just right. My set up is echo-e on a KGO1100 and echo-e on a Riva1100. Both of these batts come off the charger at 4.2v so they vape at a true 3.7v. My juices are 18mg. The kicker though is I also found that MadVapes cappucinno 80/20 in 18mg holds up very well with flavor/th and vapor in an echo-e and cost half as much as the Halo products. Previously I was using the MadVapes cappucinno in a dual coil, CCV carto and the flavor was better but not by much.