I have not studied "Standing Three Circle Qigong" so I cannot comment on the differences from Spring Forest Qigong.
There are tens of thousands of Qigong movements of varying degrees of usefulness and complexity. Spring Forest Qigong is a series of easy-to-follow movements that work specifically for health and well-being. It is considered "medical Qigong."
It is best to pick one form of Qigong and master it. Practice it for years. If you are not completely satisfied with the form you are practicing, then try out another form. Window shopping is fine as long as at some point you focus on one form. Otherwise you will miss many of the benefits of practicing Qigong.