Ali-Frazier is the clear #1.
Barrera-Morales is the clear #2.
3rd place is close, but I give the edge to Bowe-Holyfield.

As much as I loved Ward-Gatti, I can't put it top 3, because there wasn't as much at stake as there was in the other trilogies. They weren't fighting for titles, PFP status, etc.

I loved Morales-Pac, but I can't rank it as high as Morales-Barrera. A real trilogy or rivalry has to involve some level of hatred or dislike. Morales and Pac actually liked and respected one another. You definitely can't say the same about Morales and Barrera.....