There are so many opening themes in RPGs, i'm not sure where to even start while limiting myself to just a few

Nonetheless, I'll do my best with some shout-outs.

Xenoblade X

Ar Tonelico

Tales of the Abyss

Ys Origin

Trails in the Sky the 3rd

And for variety's sake some western RPG ones (AKA the Jeremy Soule section):

Morrowind, because yes, it does deserve more credit than the Skyrim version

Guild Wars: Eye of the North

Guild Wars 2