I think it will be close between Barrera Pac and Jones Trinidad.

I voted for Jones not because I think he's a major PPV draw any more but Trinidad is one of the most popular fighters of all time and I'm sure loads of people would tune him to watch him get a beatdown.

Jones vs Trinidad 460,000 +
Barrera vs Pacquiao 450,000+
Cotto vs Mosely 390,000 +
Vargas vs Mayorga + 200,000