I have ventured into the box joints for my corners and love them. It is more work but looks 10 times better and will more sturdy.
I got the plans off of www.beesource.com build it yourself page.
Normally you would make a 3/4 wide joints but my table saw would not accommodate that wide of an dado blade, so I half that and used a 7/16" dado. This is what a corner looks like.
I will make a few medium supers and going to make a few nucs also.