Alexander and
Cole are my favourites. I also love
Samuel but if it isn't a favourite of yours, then it isn't worth discussing when there are nice alternatives!
Alexander Cole or
Alexander Russel both sound great.
Alexander isn't too popular IMO. It is a classic and timeless so it is always somewhat popular but not to the point of annoyance. Its just like
Catherine really!
Cole is more trendy but still nice.
Cole and
Cate are cute, but not cutesy and they won't be Cate-and-Cole their whole lives. For most of his life he will be just
Cole so its important that you choose a name you love.