Kakashi wins!
One armed Raikage is easier to deal with than two armed Raikage.
If Sasuke was able to put a scratch on Raikage's shoulder with an A-Ranked Chidori than Kakashi should be able to put a hole in Raikage's heart with an S-Ranked Raikiri.
Also it shouldn't be too hard to predict where Raikages attacks are going to come from since he only has one arm.
Also Kakashi has Kamui which could take Raikages other arm or his entire head.
Hidden Mist Jutsu could also keep Kakashi out of sight so he wouldn't get blitzes by Raikage all day and then assassinate him with silent killing and a Raikiri to the neck.