I prefer the Mini because it comes with an RBA so you have the option of building your own coil/wick set up. Even if you don't think you will use it right now, it;s still an option down the road. With the Nano, the tank capacity is less and it only accepts the Kanger coils. It still vapes well though, so it depends on what you want.
Also the Nano will be a bit cheaper up front, but will cost more in the end as coils cost a lot more than wire and wick (for the RBA on the Mini). You can also rebuild the stock coils but I prefer the RBA.
Solid advice. I went Mini this time around and have already added an RDA to the mix (Mutation X v3) Haven't tried out the RBA that came with the Mini, but judging from the fun I'm having winding my own coils with the RDA, I'm really glad I have it available. FWIW, I went with an iStick 50 for now as I'm still figuring out if I want more power or temp control in my next box mod.
To the OP: I can't recommend the Subtank Nano / iStick 30 enough. Small, affordable, works. Even though I've moved on to a Subtank Mini / RDA / iStick 50 and see a more serious box mod in my future, the Nano 30 combo is just so totable and the perfect "take with" setup
My fantasies of saving money quitting cigs is just fleeting memory...