I dont love the carta, the atomizer heats up too quickly almost burns the oil sometimes, the bowls are smaller than the competition, I also dont really love the quartz and titanium they offer either. They also seem to be having a bunch of issues that theyre working through withbthe atomizers, bases and the app. The main selling points are the bluetooth control (which may or may not work) and the removable batteries
The peak is more expensive but they seem to have worked through most of their issues. If you follow their instructions and keep your stuff clean you shouldnt really have any issues. i use mine every day and havent needed to change the atomizer once this year. i would recommend an atomizer rebuild kit just to have in case though.
The kandypen is brand new Their lifetime warranty is the best but not much info out there.
And the hyer is the closest to a banger/rig and/or enail. If you have a lot of glass that you own and like to use its a neat option but obviously not as portable as the other options.