So easy. I love the soundtrack from Super Paper Mario. Its variety of tunes can fit any situation, and Brobot L-Type and the Underwhere are very very amazing! Super Mario 64, Yoshi's Island, Mario & Luigi: Bowser's Inside Story and Super Mario World are great too.
Though I'm shocked nobody has...
I can't do a top 5, it's like picking a favorite child! But...I'll say a few games/franchises that stick out to me.
Kirby (Particularly, Super Star Ultra, Squeak Squad and Return to Dream Land)
Undertale (Call me trash, I don't give a tem! Undertale is a masterpiece of an RPG)
Sonic the...