"You're welcome" is more formal and proper. People will often say, in everyday situations, "anytime" or "it was nothing" or "my pleasure." I often shorten it to just "welcome," but that's simply out of expediency and is more part of my own idiolect.
Hi, they both sound fine to me, you can say both when talking to a friend, but I would suggest that "you're welcome" is a bit more formal. I wouldn't say "anytime", to a teacher, for instance. Sorry, Bibliolept got there first.