Thanks for the input! They feel of different worlds to me but that’s probably because I grew up in Germany and didn’t know anything about Welsh language or culture until I was an adult.
My partner is very passionate about Welsh language preservation and the kids get my German last name so we leaning more towards a Welsh first to balance it out 
But incidentally partner has some German ancestry as well (great grandparents came to Wales from Germany because of WWII) so I think a German name would be special to both of us and is definitely an option we’re considering