I just got my first box mod and went for a modest 30 watt Sigelei Mini and I must say that I'm a huge fan of the box style vape. the 30watt is perfect for my new favorite tank, yep you guessed it, Kanger subtank Mini. I actually picked both the mini and nano up from an online vendor after locating them along with a coupon code from Gotsmok.com. Up until this current setup, I had been using other Kanger tanks on a Sigelei V5 which was my main device of choice for most environments.
I'm not a super huge sub-ohmer like some, and tend to build to around .8 ohms on my regular mechanical mod. I've noticed that the lower the ohms, the more airflow you need. My buddy is building .15 ohm coils and is looking for a box. There's some handy watt apps you can download for your smartphone that will convert volts, amps, watts, and ohms which I find very useful. I think we determined that he would need 150 - 200watts box mod if he wanted to continue building to such low ohms.
I'm quite pleased with my Subtank and have hardly touched my Orchid since getting it which had been my favorite RBA/RTA.