I will now add my thoughts. You can't get much better than a DNA chipped device. When someone says whats the best mod, well it isn't so much the mod but the chipset controlling it that makes it.
Smok and a lot of other chipsets aint much cop to be fair. So You could buy something that looks so nice, but fails in respect of being a good device because the chipset is not to good.
Ok a DNA will cost anything from About £50-120 but you get what you pay for. Others that are worth a punt are the Voopoo Drag 2. Vsticking 530.
Those 2 have really good chipsets that work as they should and are around the £50 mark for a 177w-230w mod.
All you really have to do is find something with a good chip that you like the look of,
Smok have had a lot of issues with devices over the years same with Ijoy. So my advice is avoid those 2. Oh and check Voopoo website the Drag2 may still be $45 which is a steal.