Nothing really has changed with the way resource packs work. At least not to me. Also, it isn't difficult to change the types. I use Zamar to covert media files to .ogg format and I use vlc to listen to them.
Also, I don't really need suggestions now. I'm thinking of putting of a bunch of Kevin MacLeod songs in it. (He made all those songs you hear in Minecraft videos and the like. Here's one you might know.)