Psychology Theories

I was very intrigued by our previous class where each group represented a theory and explained how their theory saw results to each experiment. There are very distinct theories that make up the psychology field. Each has opposite views from the other. But how do you choose which theory to support? Yes you shuffle through your own beliefs and see what fits; but, at least from my experience, there is never just one theory that all my beliefs fall under. I agree with a lot of what the existential theory says, but I also agree with a little bit from behaviorism and psychoanalysis. Does that mean I should support existential as my theory of choice. Another thought I occasionally think about is: since each theory is so different, do many people solely represent one theory any more? In each of the psychology class I have been in since I started college, each professor has said that they use techniques and theories from each major theory. They tend to have one theory that they lean towards, but they pull from other theories, as well. In a sense, it is as if they are making their views “complete” by combining theories to form one. One therapists cannot necessarily be completely successful with every client they see unless they use bits and pieces from other theories besides the one they mainly support. Since it is becoming more common to “complete” one’s beliefs by combining thoughts and techniques from multiple theories, how many people are left who solely represent one theory?