The problem with alternate Spanish anthems is that there are very few examples to choose. Even the
Himno de Riego was polemic during the Second Republic, for being very lame as an anthem. I've even heard, but I cannot check it, that during the First Republic they were about to give up and consider to keep the
Marcha Real, go figure.
The
Trágala could have been an option, being a constitutional popular song, but its popularity faded away after the end of the Civil War, that's why
this awful version is the only one I can find in youtube...
Finally, it's a shame that Albeniz's
Asturias (leyenda) doesn't fit well with the martial, simple sounds expeted from an anthem, because it's the best Spanish patriotic song ever made.