The Roughstack V2 is limited to 3.7 volts. The Roughstack Maxi is larger and able to accommodate different batts for 3.7V-6V & 7.4 V vaping. I would prefer the vaporluxe since you can adjust the voltage without having to buy a lot of different batts. But for the $150 pricetag I would recommend the Provari or you can pick up a Lavatube kit for $100.
I do not have any of the units you are looking at so I can't say whether they are good or not.