While similar in many ways, the agencies have different features and requirements for submission on their sites. These are the things that I considered when I decided to become exclusive with Dreamstime.
1. Some sites seem to accept anything, which to me, gives their sites a substandard look.
2. Others seem to want a photographer that is a "jack of all trades". They don't take into consideration a photographer's particular or specialty, which could actually be a benefit to an agency.
3. Some, while quite good, seem to prefer a particular look for all their images, which does not give the designer many options.
4. I found some sites difficult and confusing to navigate which, if frustrating for a submitter, must also be frustrating for a purchaser.
5. Some sites depend only on the quantity of sales for their contributors and provide little incentive to produce quality work.
6. All of the agencies represent many of the same contributors and images. Does an image lose it's impact when seen over and over again on many different sites? I think yes.
I felt that I would rather put my efforts into doing the best job possible with one agency. I chose Dreamstime. In the first month, I concentrated on becoming familiar with their expectations and requirements. By paying close attention to which images were accepted and regected, I was able to raise my acceptance percentage to 81%. By taking care to improve the appearance of my images in Photoshop and by uploading 139 images so far, I now have 90 downloads in my first two and a half months. By taking advantage of the marketing programs and becoming involved in the community, I hope to develop name recognition. By continuing to increase the uploads to this site, I can see a good income in my future. I am convinced that these things could not be accomplished if I were contributing to many agencies.