I don't think it's a toss-up, I would take Francis.
Both of these guys figure to have ratios that fall somewhere between "OK" and "CRAPPY". Sure Ramirez may grab a extra win or two all things being equal, but he Ks no one. If you are playing roto 200 innings of a guy like Ramirez will doom you a finishing in the bottom half of the league in Ks. Finally, while I do not believe that Mazzone is quite a diety, a lot of people do, and he is not around anymore.
Francis, on the other hand, has a decent K rate that figures only to get better.
Frankly, Coors really slid as an offensive park last year. Still a strong pitcher's park overall, but I am not so sure that it still spells RIP for a quality pitcher. Maybe the humidified balls are working. Regardless, I actually like Francis as a potentially productive sleeper for the back of the fantasy rotation.