There's a bunch of these things coming.. the segway was supposed to 'revolutionise human transport' and all this hype. Turns out it's only useful in certain circumstances and it was just kinda before it's time - you're just not cool on one. We're on the brink of a whole new bunch of reinvented segways..
The onewheel is cooler than the others in how it goes off road, and on the beach. Pick of the bunch if you like off-road. Plus surf stance, although I think you won't get much carve outta those tyres.
For around town, one of these two designs would offer some other potential advantages including price, range, faster, bigger diameter wheels, and easier to carry on public transport etc.. Both of these styles have a whole bunch of brands but essentially the same, and about $250 each in bulk on Alibaba and ranging up to $1000 with some branding and markups slapped on top.