I am British. DH is German. We live in Germany but spend a lot of time in the UK.
The name must be pronounced very similarly in both languages, if not the same. This means no 'th' sound, no 'j', no 'e' at the end. R can also be a problem.
The name must also be spelt in a logical way that comes naturally to both languages. C and K can be problem letters here. As can Z and S, and sometimes C and Z.
The name cannot be too modern or too old-fashioned in either country. Fashions in the two countries do not correlate with each other.
It should not be too biblical, too nerdy, should not be the name of people we know, or people we disliked at some point in our lives. It can't be too long, start with an M, or have any negative cultural associations.
It would be nice to have a nice nickname potential, and a not utterly hideous meaning.
Oh and it can't be French. Or too British or too German.
I think the next one will be named Bob. Regardless of sex.
Tell me about your criteria!