I started with clearos (ok, but not the best flavor, tend to leak lightly for me), then vivi novas (similar to clearos, usually less leaking, replaceable coil is nice) and Kanger t3s (gurgling, which leads to them spitting juice in my mouth, dislike) protank (OK, but a bit cool vape, light on flavor), now a carto tank (better flavor, but cartos don't seem to last as long as clearos or heads on VNs/Protank). But my favorite so far is a Smoktech drunker tank, which is a silica wick based rebuildable, sort of a step in between gennie type RBAs and clearos, I guess. I haven't learned to do the coil and wick yet, but you can buy replacement coils for about the same price as Vivi or Protank heads, though they are a little more involved to replace. But the flavor is far superior to everything else I've tried so far. Not sure I can really speak to how long the coils last, as I was using a very dark juice that seemed to burn out all coils very quickly and now I'm out of pre-made coils, so I have to wait until more come in, or maybe finally figure out how to build one myself (look out for a thread a may start sometime soon with questions).