Putting aside their personality both are great players and both are (were) legends in Italian football. Old Totti had many qualities in his sleeves, just like Del Piero. I think there's no way Del Piero had better vision than Totti, same goes for passing. Totti excelled at it and he was controlling the whole pitch back in the days when he had Cassano next to him. His through balls, passes to switch flanks and heel passes were on whole another level. He was a different player compared to Alex, he just had other qualities. Both had amazing free kicks but I'd say Del Piero was better at it, same goes for ball control.
Saying how he stayed in Rome because he's a big fish in a small pond is a weak argument. Many players decide to stick in their team for many reasons (Marchisio, De Rossi etc.). Totti also had superb lob shots (his goal against Inter is probably one of the best I've ever seen). Then again, how time went by, Totti's qualities easily started to vanish and he wasn't in the highlights of Roma's play, unlike Del Piero who always carried Juventus and showed consistent level of quality matches. Del Piero didn't cut it in Italian NT, that doesn't mean he was a lesser player because considering your take on it, one could assume that. That being said, I have no idea who would I pick as a better player. Both were great, but both had different qualities to offer.