I’ll say this. Both are among the best fighters to re-watch over and over. Napoles I do feel is definitely the smoother, more complete fighter, Olivares the more explosive and powerful. I’ve said it for years that along with Matthew Saad Muhammad he’s the most consistently exciting fighter that’s been extensively caught on film. What separates them on the all-time lists is probably Olivares’ losses because on quality wins they are close. Olivares had some incredible wins like Rose, Castillo, Chacon. The Olivares that beat Rose (a great fighter) is one of the most ferocious and brilliant fighters of the last 50 years.
I probably rate Napoles a bit higher and think he was the slightly better more complete fighter but Olivares's run to the title doesn't get anything like the credit it deserves, it was incredible even before he started dominating other great fighters. He cleared out a shedload of good fighters in brutal fashion and was fifty odd fights for zero, nearly all by KO.
I have no problem with you disagreeing with the second part. I don't see how the first part is up for debate. Welterweight is without question deeper all time than Bantam. The welterweight GOAT is the consensus P4P GOAT, the second greatest welterweight is a top 3-10 ATG.