I'd make a clear distinction between "interpretation of quantum theory" and "alternative new theories". Quantum theory in its minimal interpretation (a theory without an interpretation, i.e., without making contact to real-world observations and experiments is not a physical theory at all) defines a clear mathematical scheme and how it is applied to describe the phenomenology they are applicable (sometimes in exact ab-initio solutions of the quantum-theoretical equations, often in terms of approximations like perturbation theory in QFT) to make predictions that can be experimentally tested. Personally, I'm sticking to the minimal interpretation, because it's minimal. In my opinion, a physical theory is complete as soon as I can describe all known reproducible observations with it (that's the status of QT today) or as soon as I have found an experimental fact contradicting it, which doesn't make it obsolete completely but it leads to certain constraints on the applicability range of the theory. That's the case for all of classical physics (Newtonian mechanics was found to be invalid at high velocities and then has to be substituted by (special and general) relativity, electromagnetism needs the extension to relativistic field-theoretical descriptions (first the classical kind a la Maxwell); all of classical physics needs to be substituted by quantum theory after all, etc.). It's pretty likely that also quantum theory one day may be found to be an approximate description of Nature by finding some empirical contradiction to it and it must be substituted by a more comprehensive theory. That's progress of science and thus should not be taken as a "failure" in any way.
Some people are, however, not satisfied by the minimal interpretation because of its probabilistic nature, and they try to find other interpretations of quantum theory. These other interpretations lead to the same predictions about the outcome of measurements and thus from a physics point of view it's still the same theory. There are, however, different categories of "interpretations".
The first category are different mathematical techniques applied to quantum theory. This already started in the very beginning of quantum theory in 1925, when nearly at the same time, Heisenberg, Born, and Jordan came up with what is called "matrix mechanics" and Schrödinger with "wave mechanics". Independently Dirac came up with another formulation which is the most general one and was called "transformation theory" at the time. From the modern point of view, I'd call it representation-independent formulation. The non-relativistic QT was then completely formalized and understood by von Neumann in terms of Hilbert-space theory, which more recently has been reformulated in terms of the socalle "rigged Hilbert-space" formalism, which makes the hand-waving maths we physicists use in our calculations a mathematically strict formulation. Another equivalent (but as far as I know less strict) formulation is then Feynman's path-integral formulation, using functional methods to express the same theory. All this is not "interpretation" in the more narrow sense, but just different mathematical language to formulate the same theory. Which mathematical formalism you use doesn't so much imply which interpretation you follow, although often the path-integral formalism is interpreted somehow in the sense as if it were a new interpretation, a view also Feynman seems to have hold for some time. I think, that's not the case. It's just another way to express one and the same theory, and I (as a follower of the minimal interpretation) can use any mathematical tool without changing my view on interpretation. Which one I use, depends on the problem I like to solve and which one I'm able to use for that problem, but it's totally unimportant concerning my view on the interpretation.
The second category is to add some elements, concerning the philosophical implications of the theory. E.g., in Bohmian mechanics, one adds a kind of "trajectory picture" back into the physics of single particles which has been abandoned before due to the uncertainty relation that states that a particle cannot be prepared in a state such that both position and momentum are both determined to arbitrary precision, which implies that it does not make sense to talk about trajectories of a particle in phase space as is the case in classical mechanics. The Bohmian trajectories are determined by non-local equations with the "wave function" of the particles as "pilot waves". On the other hand it's still an open debate, whether the Bohmian trajectories are observable or not and if so, whether Bohmian mechanics is experimentally disproven already. I think we can say that's pretty undecided today. The same holds for other interpretations as the various flavor of the Copenhagen interpretation, which is a rather vague conglomerate of different ideas like "complementarity" (Bohr), "collapse of the state" (Bohr, Heisenberg, von Neumann), the "cut between quantum and classical behavior" (von Neumann). In my opinion the "collapse idea" is pretty useless if not misleading. At least it brings more problems with it than it solves with regard to Einstein causality in relativistic physics. This was already critizized by Einstein, Poldolsky, and Rosen in their famous paper. Then there is "many-worlds theory", which introduces the quite funny idea of parallel (unobservable!) universes, splitting up at every time one observes some clear fact about a quantum system. I never understood what this bizarre idea might solve in terms of the philosophical quibbles some people have with the (minimally interpreted) quantum theory and its probabilistic nature.
All this are, however, legitimate questions to be asked, and answers to them might lead to a deeper understanding of quantum theory. Of course, anything which doesn't lead to observable consequences that contradict quantum theory in its minimal interpretation, doesn't lead to a new theory in the sense of natural sciences and thus one can well say that such discussions are off topic in a scientific forum like this, and it's as legitimate to close threads on "philsophy" (humanities) without "scientific content", which of course includes also this posting itself ;-)).
) who basically thinks it's all pretty silly, and that the whole business have more in common with "religious war" (experiments is a waste of time since we all get the same results), than fundamental science.
