For casual/mobile gaming i think iOS is the best platform right now and the users are more willing to pay for games. Problem with both iOS and Android is that the number of apps are huge and it's hard to get noticed. I do not think touch devices are good for hardcore games. You can do some pretty good stuff on tablets but you are still limited by the input. I think both iOS and Android will stick around for a long time. The portal market have declined in favor of the mobile market.
For indies currently PC/Mac/Linux seems like a good combo. With PC being the best platform. And getting your game on Steam, Humble Bundle etc are really good for sales. Ouya seems like a great indie console. It's still too early to say how the console will do but Airtight Games
recently announced an Ouya exclusive.
Using a keyboard or a controller allows you go to make more complex games. So games made especially for Ouya are less likely to play well on a touch based Android device. There are of course other Android devices that uses similar inputs like Game Stick and Project Shield. These devices may turn into a market of their own as they offer hardcore controls and are easy to develop games for. Ouya is the one with the most support right now and Shield is targeting a different market.
For a small indie developer I think the best platform right now is Ouya. After the official launch in June there will be I guess 100,000-200,000 owners. Which is extremely few compared to other markets. But there will be only about 100 games to compete against. Your game is very likely to be noticed by a large percentage of the userbase, especially if it's good. These people also want games to play on their new console, so they are also more likely to buy games.
