The best review of electric skateboards is found here at TechGearLab.com. They do a great job giving specifics on the strengths and weaknesses of each board, how they tested and scored each. Click here for the article.
In summary spend over $1,000 for any of their top three picks:
1. Evolve GT Bamboo Street
2. Boosted Board Dual+
Or, if you want to spend under $500, then go with the Yuneec E-GO 2. Do not spend between $500 and $1,000 on an electric skateboard. You will be disappointed, though maybe not at first. All boards that get used will require replacement parts or will warrant upgrades. This is impractical or very difficult for many brands under $1,000.