I have a few, so here's a list in no particular order.

You Can't Fight The Homestuck - Broadway Homestuck (A classic!)

Pale - totalspiffage (An absolutely adorable meowrails song sung in the perspective of Nepeta)

Ave Mary Am - Broadway Karkat (Always gets me super hyped and immersed)

Dead Pr0blems - Off-Broadway Aradia (I always have this on loop x3)

Sexy Kan I - Broadway Rose and Kanaya (Something about this one is so alluring to me! It's so cute and cheesy xd)

I'm English - Melody Jake Parody (I just like it a lot, I dunno!)

Rufio Don't Call The Cops - Broadway Roxy (Ignoring some of the questionable things she sings about in this song, it is SO good)

Sober - Broadway Gamzee (While I don't like this one as much anymore, this is more of an honorable mention! This was one of the first Homestuck parodies I ever listened to so it has a special place in my heart... Though... It's not that good unfortunately)