For me, the best from Wario Land 4 has to be Pinball Zone. Bueno para relajarse. I also very much like the Jump Forever version with the added flute solo!
Strong One: Is unfortunately rather notably prone to being used in terribly ironic ways (Negative Man is one of the weakest enemies in the entire game, the Barrier Trio's power comes from intelligence/sorcery rather than actual brute force, the Heftyheads and Hippo Launchers really aren't that strong when compared to how powerful your party members have hopefully become at their points in the game, and the Masked Man's ludicrously high attack power is basically his way of hiding how pitifully weak he is on the inside), but is a song that absolutely embodies hopelessness nevertheless
Master Porky's Theme: One of the greatest final boss themes of all time, and also a perfect send-off for the game's "Porky" leitmotif
Battle Against The Masked Man: Yet another one of the greatest final boss themes of all time, and also one of the most disturbing
And El Mariachi: Don Flamenco as portrayed by Punch-Out Wii, is that you?
Smashing Song Of Praise: Don't even get me started on those mood shifts of its
Well, it might not be the best soundtrack I've ever heard, (I still think the SNES Donkey Kong Country soundtracks are the absolute best), but Shake It! definitely has the best OST of any Wario game. (With that of Wario Land 4 being second IMO.)
Do you ever have that thing where a random piece of music pops up in your head and you don't know where it's from?
Well, I had that today, and although I knew it was from a Kirby game, I didn't exactly know from which one, since I haven't played one for a long time, but after looking through OSTs I found it rather quickly.
This might well be the most underrated theme in all of Kirby history. It's titled The Hero of Dreamland and that's exactly how it sounds: a very heroic and triumphant theme that perfectly captures Kirby's brave and heroic spirit. Let's hope this awesome theme will make a return someday.