Alphonse definitely makes me think of
Alphonse Elric.
I like
Alonso and maybe
Afonso, but some of the variants with "
Alf" or "Alph" sound... silly maybe? "
Alf" on its own sounds like a silly dog name, so that's how I view the whole name. .
I think
Alphonsus looks stuffy and overimportant.