In order - for me:
English
Mandarin
Spanish
French
German
And yet the only ones I know anything of (beyond menu items) are English, French, Japanese and Korean.
But other than English and Mandarin (because of their extensive usage), the selection would be highly influenced by your own geographic, cultural and business concerns.
The inclusion of computer languages is a case in point. That is critical knowledge for programmers and some of us geeks, but totally useless (even risky) for most computer users in the average company.
As for Latin - total wasted effort. (Yeah we took it in the old days - pre 1970s) You will learn the same structures and most of the etymology taking a FAR more useful and viable romance language such as Spanish, French, Italian or Romanian.