Judging by the limited time I've seen them on TV, it would definitely appear that Obama has the most engaging personality.
However, when presented with tough questions, Obama often doesn't seem particularly well equipped to deal with them. Perhaps it's partially intentional I don't know, but it seems his discussion of the meat of some arguments is often lacking. Both Clinton and Edwards seemed to handle the topics better IMHO. OTOH, Clinton often comes across as dry and institutional.
One cannot deny the importance of charisma in a leader, but as the results from yesterday have suggested, a lot of people value more knowledge and experience in a prez candidate as well, for obvious reasons.