A valid question. The best answer is flexibility. On AMD64, I am guaranteed to be able to run pretty much any OS I want if my needs should change. OpenBSD, FreeBSD, weird Linux distros, whatever. Comparable ARM boards, however, tend to only work with Linux and have highly variable levels of support at that. Support can wane depending on interest and level of involvement of the community.

A Raspberry Pi would be an excellent choice if they ever offered one with multiple gigabit interfaces. But it's the only ARM board I would currently consider for the role.