You said it yourself: nobody would. It's popular to hate on the GBA versions of the Final Fantasy games and deem them inferior to the SNES versions, with detractors citing soundtrack differences as one reason among several.

While I disagree with you and everyone else who shares this belief, it's for different reasons; I think questions like these fail to understand the immeasurable when we are discussing not just video game music, but any piece of music - any piece of art, for that matter. No piece of art, film or music is objectively good; there is no such thing. We can attempt to make sense of it through purely objective terms, such as whether colour x is able to blend well enough into the painting, or how wide angle shots of battle scenes in films are able to accentuate a mere movie into a spectacle, or how a group of notes work for a particular chorus, but that is all we are doing. We are literally making objective observations of things that are telling us to feel something. It's never been about objectively grading pieces of art - that can come later on - it's always been about feeling, introspection, and subjectivity, or at least this has always been the primary focus. Why do you think normal everyday people (not critics) go to museums, or art galleries, or the movie theaters?

And I am not saying one ought to abandon objective reasoning altogether - far from it. In most areas of my own life, always opt to make sense of our world through a strictly analytical perspective; I don't like to make my worldviews based on how I feel about things. The one area I disagree with this approach is towards music, or art, or film, or video games. You have to consider the immeasurable, the emotional connections, the emotional attachments when you talk about them, whether it is the anger, sadness, happiness, boredom, something, some feeling which it wishes to elicit from us, and in fact DOES elicit from us, whether you realize it or not. As such, we cannot exclude this.

With that said... I do enjoy listening to both the SNES, and the GBA soundtracks of the FF games that were ported for the GBA. While the SNES ones sounds much smoother, consistent and achieves clarity in both style and substance, the GBA ones are, admittedly, much more abrasive, aggressive and different - for a lack of a better term. Well then why do I still enjoy them? Why do many others still enjoy them? Many reasons: nostalgia, many (including myself) grew up on the GBA version of the game, and know FFVI as the GBA version, and many find the translations and added content to be a worthy addition to an already well-crafted game as demonstrated through the SNES. As for me, I simply feel that one is not better than the other, it truly is subjective. Also, this is what I have been trying to argue with my uploads: that the soundtracks would probably sound infinitely better if they were ripped directly from their games and not be subject to poor sound hardware.

Now to be fair, I have no idea of the nature or intent of your question; I was actually sort of waiting for someone else to chime in, but nobody did, and here we are,

Tl;dr: Music is subjective; we shouldn't be picking and choosing which song or version of a song is the "best". There are people who absolutely love both soundtracks, there are people who love the SNES version, and there are people who love the GBA version - simple as that.