I'll vouch for the Ravens. I like them a lot. I had some issues with filling the tank
improperly and getting loads of dry hits, but now that I realize what I was doing
wrong they work great.
I'll try to explain what I was doing wrong. I was filling from a regular
e-liquid bottle and may have been blocking the opening, preventing air from escaping
as I filled the tank. I started using those screw-on blunt syringe tops and have
not had that problem since.
I don't have nearly the experience that other folks in here do, but these things provide
about 50% more flavor and vapor production than anything I've tried. That includes
various top-coil clearos (only the iClear30 was satisfactory to me),
regluar cartos, and bottom coil clearos like the Kanger T3, Evod,
and ProTank. I still enjoy and use all of the bottom coil devices.
But the Raven+tank setup is my favorite. And I've never had any leaking problems.
I've used both the flanged and non-flanged, in a few different tanks. I'd suggest any
tank with a fill hole to make life easier.
What I AM curious about is how these compare to bottom feeders, which I've never used
but am extremely curious about.
Anyway, apologies for being long-winded. I hope this helps someone out!