My all time personal fav is

Hagler/ Hearns

followed by

Barrera/ Morales 1

&

Castillo/ Corrales.

Fights I love to re-watch:

Leonard/ Benitez
Pryor/ Arguello 1
Ali/ Frazier 3
Olivares/ Arguello
Tua/ Ibeabuchi

Theres many more but I tend to visit those a lot