The “Dodo Bird Verdict” is an idea first proposed in the 1930s, stating that basically, any therapy style is as good as the next. There’s some truth to that idea, as many of the qualities that make a good therapist are present no matter what your theoretical orientation might be.
However, recent research has shown that not all therapies are equally effective. Here’s an article describing a study comparing Cognitive Behavioral Therapy (CBT) and psychodynamic therapy in the treatment of Bulimia. The briefer, more symptom-focused cognitive-behavioral treatment brought about significant and lasting improvement when compared with the more long-term psychodynamic treatment. For the 1-2% of the population who suffer from Bulimia, this is great news!