Which market (that of Android games or that of Flash games) is more profitable and will give me a better chance of success?
Where can I find the relative market shares of these markets, globally?
I have little experience about this topic but by logic and knowledge I can give a few pointers that might be worth a few pennies.
First of all: those two markets are big, I mean really big, maybe, just maybe, too big for you. This is good as you have a large target audience, but the size already has attracted many many many (you are not the only one, no) game developers, this market is largely saturated. Most games won't even be recognized due to the sheer number of games there are. You won't make a penny this way, at best you will get a balance of 0. You'll need a better plan than just making a game and selling it.
The most important difference between Flash games and Android games is that Flash games are pretty much exclusively financed by ads while Android games are partially financed by ads, partially by selling the games themselves and partially by in-game purchases.
For the customers that means they don't have to pay for their games, they can play as many games as they want and can try out any game at any given time, this means, in the end that if your game is good it will get at least some attention.
The downside is, you are bound to have a lot more people to play your game, because the average every player will just give you a penny or two as opposed to a dollar or two for android games.
You might want to consider other, smaller, markets, such as the PC Indie market. The target audience may be a lot smaller, but you will be able to get ground much easier as your game isn't one of millions then but just one of hundreds.
A good game sells itself no matter if it's on app stores, facebook, kongregate or self-hosted.
What you should do instead of trying to figure WHO you want to make a game for, make a great game. Then you can sort out where and how it's best marketed.
But of course choosing a market with millions of users, against one with only thousands has the potential of bigger profit if it succeeds.
I like self-hosting and facebook apps, for the simple reason that noone tells me what game to make, and how i intend to profit and so on. The bad thing is that it's much more work getting noticed.
Android apps because it is a broader market. I don't know where you could get market shares. Sorry.
Depends on what you wish to do. Generally I would say Android. Market shares is on the stock exchange. What was more successful crush the castle or angry birds and why?