For what it's worth, it's very clear to me which is better even on my iPhone's speakers (as well as on my desktop's "real" speakers, of course). Sound preferences are deeply personal, but I'm still pretty shocked GP can't tell.
Consider hi-fi speakers vs monitors. The difference is very clear, but it would be somewhat wrong to call either "better".
This is actually a common misconception. In blind testing, the average listener reliably prefers the more accurate speaker. There is a talk [1] by Dr. Floyd Toole that is an excellent crash course on the science of sound reproduction and listener preference.
I listened on a calibrated speaker setup and on my good Sennheiser headphones. Yes, there’s a difference, but both sound like shitty speakers just with different EQ profiles applied to it. It's still compressed to hell and extremely tinny no matter what.