Firstly, ask your pharmacist if they sell the Mighty, or the Mighty+ if you want to push the boat out. My clinic offered me the Mighty for £196, and that's about £50 cheaper than you can get the Crafty on amazon and elsewhere, and the Mighty is an upgrade on the Crafty for sure. You can get devices cheaper on prescription in most cases than buying them online.
I know nothing about the Nectar Hex, although it's definitely the cheapest of all the options, but in the vaping world S&B still hold the crown.
Although I can't really say I'm comparing them on a scale of vapour cloudiness, because that's usually a measure of how much
THC you are
not consuming, but instead wasting. I get the desire, but it's not really worth seeking out cloud production in a vape at the expense of other things... and
to be honest has far more to do with the quality of your flower than the quality of your vape. As long as your vape gets up to temp and has a decent vapour path, any vape will be capable of making clouds with high quality flower.