I would need to know a lot more information about what you shoot and what type of images you are planning to supply the stock industry. While the money in stock is not what it was in the 1990's, there is still money to be made, if you are producing the right type of images. I would suggest you spend a bit of time on the sites of Corbis, Getty, Offset or Image Source and see what type of pictures they are featuring. I would then search for the type of images you are producing and see if they handle such imagery. I will tell you that travel and landscape are the hardest type of images to get any return from.
Getty, Corbis and Image Source share between 30-50% of revenue with their photographers. The question is not whom has the highest percentage but the highest percentage of what. 100% of a buck is not much. Also, support from ones agency is helpful. There was a time when agency gave photographers real life editors with whom a photographer could communicate with and generate ideas. Except for a few exceptions this is no longer the case at Getty or Corbis. The other insult or time suck with Getty and many of the Micro Agencies is that the photographer has to provide fully retouched and keyworded images before the agency decides whether to accept those images.
While I have contracts with Getty, Corbis, Blend, and AgeFotostock, I am currently giving almost 100% of my stock production to Image Source.
Sincerely,
Zave Smith
www.zavesmith.com