Since, everyone seems to be asking me if there’s root method for AT&T Galaxy S4 MF3 (and I don’t think I can respond back anymore to the same question over and over again), you can root it using Verizon ME7 root method!
For those of you already rooted, I suggest you do not update to the latest MF3 firmware as you will be able to root it but you won’t be able to install custom ROMs as there’s no way to install custom recovery yet!