Mamma mia is the song that comes to mind when you think of abba. Its so addicting! I don't care what people say, that song isn't pop, it's rock. SOS makes me wanna get up and dance every time! I do I do I do I do i do is classic abba and I love the sax part in the beginning. I've been waiting for you sounds sort of like the partridge family to me, idk why xD. And omg I can't believe So Long did so horribly when it was released as a single, it instantly became one of my favorites. This is really when they became abba! Such a classic!