In terms of the pullup/chinup/pulldown type exercises, I think that close grip supinated chinups are the best because you can use the most weight. I believe this is because the workload is shared most efficiently between your lats and your bis. Wide grip and overhand grip place more work on the lats. But no matter what, when you do chinups, not ALL of the weight corresponds to increasing the tension on your biceps. My favorite biceps exercise is dumbbell curls. For gaining raw strength curls are probably not too important - that that is simply because not many feats of strength rely on the biceps alone. If you were to measure someone's strength by how much they could curl, you would become stronger my doing curls, not by doing chinups. And since in the beginning stages of bodybuilding, strength = size, curls are the best exercise for bicep size. In the same way I think that Z-bar extensions are a better tri exercise for mass than benching is. But for overall body mass, chinups are a better exercise since they work more muscles. I love doing weighted chinups followed by a drop-set without the belt/DB.