Slightly tooting my own horn here; In case anyone is interested in a (trivial) comparison between them I have a tiny example project implemented both with Eigen

Slightly tooting my own horn here; In case anyone is interested in a (trivial) comparison between them I have a tiny example project implemented both with Eigen and Arma (And Fortran and Python/numpy and Julia, FWIW): https://gitlab.com/jabl/tb https://gitlab.com/jabl/tb