Which is the most common spelling for the mans name charlie or charley?

The correct form of name is 'Charles'.

'Charlie/Charl' a common nicknames for 'Charles.

'Charley' spelled as '---ey' is for females, and is a diminutive of 'Charlotte'. A female form of Charles.

In other European languages , Charles is

Karl ; German

Carol ; Polish

Carlos ; Spanish

All after 'Charlemagne'/Charles the Great'. the early mediaeval French Emperor.