My SMOK M80, which was the first mod I bought after my REO in 2011 (also had a Provari from back in the day, still do).
To be fair, it's still working now, but that's not saying much as it's barely a year old and only works with one RDA because the spring has been stuck since 3 mos. after purchase. This is actually my second M80, as the first one went belly up after only a week. At least the warranty was honored.
It was especially bad since I spent more than I should have in order to support a local B&M, but it really turned me off going that route. They're the only one around here right now.
Truly, I should have known better, but I was so out of the vaping loop at that point I didn't do my due diligence.
Conversely, even though I also paid just a tiny bit more than I should have, the iStick 30W that I purchased during the time the original M80 went in to be replaced has been one of the most pleasant surprises.