Sometimes it's a pity when photo you like is not of proper quality to be accepted as stock photo or it is rejected because of being a "well covered subject". You may leave it be of try to give it a new life. As a collage, for example.
Try to seach the web for interesting tutorials to any graphic program (Photoshop, for example) and give your photos another chance - to become a good collage.
Sometimes it's enough to play with some color effects, sometimes it takes more and you can hardly recognize the original photo in the final image. All depends of your skill, creativity... and free time :)
Anyway, when rejection reasons are discarded photos you like have future again.