Fomapan 100 has a very different spectral sensitivity. Also, it is a ISO 64-80 film in most developers so if you develop it for EI 100 then the contrast goes up. The conbination of these two factors give the film a "unique" look that you might like.
Consider the Delta 100 the "ultra premiun vanilla icecream" and Fomapan 100 the "homemade dark chocolate icecream".