I started out with an UD IGO-W Plus, and it works fine. Still figuring out what coiling method and resistance to use, but that's half the fun.
I also got some free RDA from sigelei along with some other stuff. As I ordered the 20W mod after it went out of production, so i got the 30W and some other stuff for free, probably as a "sorry for the delay". But the sigelei RDA is hard to build on, in comparison with IGO-W. Now I'm waiting for my Eleaf Lemo RBA, as it's not really convenient enough to drip at work.