I suggest reading http://plato.stanford.edu/entries/freewill for a pretty good overview of the arguments in favor of the existence of "free will" (which itself has many definitions).
Which isn't to say you're wrong, but I think it's pretty uncharitable to say there aren't any "coherent" arguments in favor of free will. You did say you haven't "seen" any arguments, which I suppose is not the same as a claim that are none, but a cursory glance at that article should be illuminating for you. People have been thinking about this for a very long time, and no consensus seems to have emerged. :-)
Which isn't to say you're wrong, but I think it's pretty uncharitable to say there aren't any "coherent" arguments in favor of free will. You did say you haven't "seen" any arguments, which I suppose is not the same as a claim that are none, but a cursory glance at that article should be illuminating for you. People have been thinking about this for a very long time, and no consensus seems to have emerged. :-)
You might also be interested in http://plato.stanford.edu/entries/materialism-eliminative, which seems to fit what little you've said about your current thinking.