For me, it’s a no brainer: Yoshi’s Island. No “Level Clear!” theme has even come close to topping this.

…and then there’s the remake which manages to not only rekindle the magic of the original, but somehow improves upon it!

Nice thread idea!

There are so many embedded in my memory, but I don't think anything tops this:

This one was one of my first level complete themes.

Post more later

The Final Fantasy battle won jingle, and super mario world.

I have a few
Sonic CD Japanese
Mario Galaxy 1 and 2
Sonic Mania
I don't know if this counts but the music that plays after beating the champion in Firered/Leafgreen

Some good ones have already been named: most Super Mario & Mario Kart games, some Sonic games, the classic Final Fantasy victory fanfare.

To those, I'd also like to add the classic Mega Man stage clear theme, used in all the classic series games except 1 & 3, though remixed to some degree every time.

Some more that came to mind!