re: If Germany had developed a the Atomic bomb first who would they have used it on?

Stalingrad
Moscow
Leningrad

Then I believe they would have helped Japan with China and Australia and Italy with the Middle East. If they helped Japan then the US would have to shift more focus to the pacific.

Image had Germany, Italy, and Japan controlled Europe, Asia, Australia, and Northern Africa. They would have been almost unstoppable especially if they invaded South America and started working their way north.