If I have to choose my favorite glee cover ever, I would have to say the acoustic version of Teenage Dream.
Just because there's no word to describe how beautiful and divine this is. Darren's voice is incredibly sweet and so mesmerizing, it gives me chills every time. I find it so cute that Blaine sang to Kurt the song they met on, in such a lovely way. It makes me cry to see in his eyes and voice how much he loves him but also how much he's hurt and feels guilty for what he did. When I listen to it, I just see in my head all they've been through since they met and how much their relationship is strong. This is why I find it very sad and heartbreaking to watch Blaine sing with so much emotion and love knowing that they break up just after.. This Glee cover, Darren's version, moves me deeply. This song is just marvelous. No, it is superb. <3