https://youtu.be/hAOGtJLMHlcI love the champion theme of GSC a ton. It's hard to figure out whether I prefer the RBY or GSC theme - On the one had, RBY is the original rival battle theme remixed to such a powerful tone and is the culmination of your entire journey, but on the other hand GSC has a bit more technical finesse about it with how it's arranged.
It's pretty damn hard to say which is better.
https://youtu.be/hAOGtJLMHlc 