There's no better platforms, only more popular ones, I would suggest trying the appstore first and then moving out to the Google play store, because the price to pay to get in there is higher, blocking some of the "trash" for your game to get more exposure
Don't put your game on Kongregate or Newsground if you want to sell it
And finally, Focus on the launch, get the most attention possible, go on forums, contact the press, create some hype and such, and then let your game do the talk before slowly drowning in the sea of apps