I think that Obi Wan was the perfect mentor for Anakin for a couple of reasons. First of all the chosen one was suppopssed to bring balance to the force, so it was pretty unbalanced having all of those light Jedi running around and only 2 Sith. Secondly, if any one else but Obi Wan had trained him, he might not have gone to the Dark side, he only turned because he thought that Obi Wan was taking the training to slowly and that he didn't trust him, hence he became close to Palpatine who nurtured his impaitientness (is that a word?). So When Yoda said that "his future is covered by the dark side" he knew exactly what he was doing by allowing Obi Wan to train him. Nuff