Cranberry and/or grape is a little too tart for my liking. I have been becoming a big fan of apple-cherry juice as of late though, though that might have something to do with it being two for the price of one at the grocery store the past two weeks running.
I don't know, plain old apple juice has been on special too at the grocer, but I haven't bought any of that. So empirically we can see cherry-apple juice is way better.