"Guys Like Potter" will make you want to hug Snape, no question.
Soon after "Those Voices," Snape looks into the Mirror of Erised and sees Lily. He looks at her for a second, and then silently exits the stage in order to protect Harry and the others. Lily is left alone, and the lights fade to black...
From A Very Potter Senior Year
"I Was" is quite depressing, capturing both Harry and Tom Riddle's sadness regarding being unwanted and Harry's nostalgia for his old adventures.
"Everything Ends". The title alone kind of explains why.
Harry saying a final good-bye to Hogwarts while addressing the audience. Becomes a meta Tear Jerker when considering it as Darren Criss saying good-bye to his first superstar role and (at least temporarily) the StarKid fandom in general.