freebs2 on 08 November 2015
If I were you, I would start looking from here
http://www.newzoo.com/free/rankings/top-25-companies-by-game-revenues/
Also, you should look at results (revenues and profits) form the past 3 to 5 years, and see who is growing and who is declining. I don't know the level of detail you need, but that should be a good start.
