DMC1: Most original enemy design,
Cool setting,
Most charismatic bosses that you came to know just as well as Dante,
Most diverse in gameplay,
Most use of puzzle-solving skills,
Most kinetic gameplay,
It doesn't have any shallow characters,
Best Dante persona,
Best menacing score,
Most sadistic scene (griffon being torn to pieces).
All in all, I think CAPCOM will be pushed to beat their first installment, even after this long.