Update in 2022
I no longer promote the use of ewheels (eucs) given that manufacturers are now making them with such high top speeds which is obviously completely unsafe. So focus is likely to be on scooters, other gadgets and urban commuter systems from now on.
Update in 2020: The Kingsong S series of eWheels are known now to be among the safest. Safety should be your top priority. The Inmotion ewheels also have a good reputation & are the rebranded versions of the original Inventist wheels (such as the Solowheel). Airwheel & various other brands are known to be cheap & of lower quality. A new updated table will hopefully appear here soon but for now see HERE
Below is an old post with outdated information
New terminology suggested by the Peacemaker Foundation
The new inventions are great, but our names for them are not: electric “unicycles” are not unicycles because they involve no cycling. “Hoverboards” don’t hover and they’re not boards. Furthermore when real hoverboards appear it will become even more confusing. Here are some suggested names:
Electric wheel or eWheel (electric self-balancing “unicycle” or “euc”)
Electric Foot Scooter (Self-balancing Dual Motor Electric Foot Scooter – a “hoverboard”)
LPT (Lightweight Portable/Personal Transport: transport involving devices that can be easily carried)
Transportable (Portable transport tool)
Self-balancers (self-balancing transport tools – as listed above)
If you can think of better names then please comment or get in touch.
Viewable PDF format
Download
Word File: Electric Wheels Compared (February 2015)
PDF: Electric Wheels Compared (February 2015)
Winners Podium
Gold medal: Solowheel Orbit and Solowheel Extreme each are the winners in three categories, but they are also the most expensive.
Silver medal: Firewheel and Rockwheel also do quite well with each one winning in two categories. Hovertrax wins two categories as well but loses in four – just depends which categories are more important for you.
Bronze medal: What do you reckon? Perhaps Freeman A4.
Update: Recently a very promising and popular eWheel has been the Gotway which will certainly appear in the next edition of this table.
Author’s opinion
Personally I like the electric foot scooters because they’re easier to learn (apparently) so I bought Hovertrax which is great fun and very well built although it lacks stability at speed and only works well on smooth surfaces. If you have enough money and you value patent ethics you might wish to buy from Inventist seeing as they hold the patents. Furthermore, as of January 2015 the Solowheels generally gets the best reviews, such as on Amazon.
Great Electric Wheel Videos
I’ve looked around so you don’t have to. Here are some links to some great videos.
Fantastic review of Solowheel, Hovertrax, Phunkeeduck & the zBoard Pro. Also shows how important it is to ride carefully!
Fun advert for the solowheel
The Solowheel in London
Fun advert for Ninebot 1
Super slick super cool ad for Ninebot 1
Fun advert for IPS F400
Airwheel Mail Delivery
Airwheel stunts
More Airwheel stunts
Foot Scooter videos
Hovertrax
Chic-smart video from Korea
Links
Lean Machines: Comparison Table of Self-Balancing Dual-Motor Electric Foot Scooters
The Peacemaker Foundation 
Hi, Did I miss it, or did you leave out the Gotway? If yes, why? Tks for the chart!
Hi Uffe, when i make an updated version of this chart will definitely include the Gotway. Not included because at the time of researching, the Gotway wasn’t as well known as it is now. Recently have read good things about the Gotways. Thanks for your comment!