Given the choice of your toned AU 53 coin and the AU 55, I would go with yours for value, given the approximate $100-$200 price difference based on grades. You are a winner on this coin!
I can only agree to Chris, just clicked in and saw your post. Gorgeous catch!!! Congrats… now this little fellow will travel the world
The knees could be (ahem) "cabinet friction" as opposed to actual circulation wear of which I see none in other areas, the letters, the devices, etc. AU55 would be holding the line. You would have to show a better one for this not to be Uncirculated by modern market standards. Myself, if I were having to pay for it, I would insist on the lower grade, but I would not say XF 45, that's for sure.