It is seemingly impossible for me to list just 1.

But there are 2 fights that just stand out the most to me.

JLC vs. Corrales I - Being ringside for this fight was one of the most amazing things my eyes have ever seen.

Rafa vs. Izzy III - Being ringside for this fight was intense and just out of control.

Those are 2 amazing fights I attended that's not even getting into fights I've only seen on television.

Here are some fights I like to watch and that I re-visit often:
'Locomotora' Castro vs. 'Action' Jackson I
Barrios vs. Freitas
Gatti vs. Ruelas
'Smokin' Cooper vs. Moorer
Zarate vs. Zamora
Foster vs. Finnegan
Basilio vs. Saxton II
'Little Red' Lopez vs. Ayala
Tua vs. Ike
Rosario vs. Ramirez II
Campas vs. Duddy
Tapia vs. Ayala I
'Posion' Jones vs. John M. Johnson II
Johnson vs. Galindez
Muhammad vs. Yaqui Lopez II
Hamed vs. Kelly