You and I because it made me realize that I didn't want to be a slut anymore(not that it wasn't fun) but the song just touched me in a way that made me want to strive for something more.
Speechless, I love her voice just so much there. It's the song that made me a fan. and a bit later, I became a little monster! and I LOVE BEING A MONSTER!
Bad Romance. It was just so atypical at the time, and it not only influenced me but all of pop culture as well. It's when Gaga really became a force in the world.