Best Original Music Score, or whatever the full name is, is always a tough one to judge. To me, it's the score that best complements a film, that does not overwhelm. I have often heard people scoffingly say of some nominated scores, "I don't even remember any themes!" which I don't think is necessarily unfair, but it is a narrow view of the how and why of the score. There are scores that I would never listen to on their own that I have nevertheless included in my own Hollmann Awards because, in context, they transform or even clarify a film's tone, theme, or meaning - I'm thinking specifically of how James Newton Howard's Nightcrawler gets us into Jake Gyllenhaal's warped mindset, or even how Son Lux's Everything Everywhere All At Once is unhummable, sure, but the movie would not work nearly as well without it.
So this is how I approach this category, and I imagine, so do many of the Academy's voters. And that, finally, is how they came to pass up Björk's Dancer in the Dark and Maurice Jarre's Sunshine in favor of Rachel Portman's Chocolat (the only female composer to be nominated in Original Score more than once), Tan Dun's Crouching Tiger, Hidden Dragon (the sole first-time nominee...also the sole only-time nominee), Hans Zimmer's Gladiator (though other groups also acknowledged "wailing woman" vocalist and co-composer Lisa Gerrard, the Academy gave sole credit to Zimmer), Ennio Morricone's Malèna (this same year, he received the National Board of Review's Career Achievement Award), and John Williams' The Patriot (even if the score was seventeen cats fighting on untuned pianos, Williams would have been here: in 33 years, 34 of his scores were nominated). Of these composers, only Tan and Morricone never won before...and Morricone would have to wait another decade-plus for his chance:
None of these are bad, all of them greatly boost their films, but - if I had a ballot, here's how I'd rank them: