Is there a preferred Linux distribution for libecbufr?

Not really. Environment Canada uses Ubuntu, but that should not be taken as an endorsement or a statement of preference when it comes to libecbufr. Libecbufr's dependencies are straightforward and can be met by all mainstream distributions. Under casual testing, done outside of Environment Canada, libecbufr has performed identically well with Ubuntu, Debian, Red Hat, Centos and Gentoo.

Having said this, it is up to each organization to decide what constitutes appropriate testing and integration of libecbufr into their own systems.