I can only speak for myself but it's the one I would choose to keep if forced to choose only one. I love the 3ml carts that seem to last forever (an overstatement, of course - but they really do take a LOT of fills before the taste starts to diminish), and like the 1300mah batteries. For me, the only downside is they don't have a shut-off for the battery. Fortunately, DV sells an eight-nine-cent button protector that resolves the issue.
My basic design/usage-plan is:
a) Big, giant & humongous LRider VV with 6ML ePower carts while at home, and
b) Go-Go when out & about.
Truth be told though, I pick up that Go-Go often even when home. The combination of portability and performance are unparalleled for me. After using the Go-Go for two weeks, I sold ALL of my KR808 stuff, excluding the Elite 808's that my wife prefers. There was simply no comparison between the two. On top of which, the Go-Go Dual Coils that DV sells will knock anyone's socks off. Literally - you'll break out in a sweat if you hit it too often. I'm speaking from experience there
Steeljan once mentioned (in one of her videos, prior to her departure) that the proprietary threads might actually be advantageous by providing different, and possibly better, overall performance. I tend to agree.
I hope this helps.