One of the highest selling doesn't mean much otherwise Capcom would be spitting out a new MegaMan Onimusha about now.
Onimusha ended technically and though it was selling well wasn't selling as much as the other 4 and MegaMan before Capcom stop making MM games were selling really poorly (and I mean poorly) and that they were both made by Keiji Inafune....they seem to hate him for some reason. Plus before its decline and sudden halt MM games never sold amazing compared to SF, RE, and even MH (MM sold a lot as a series because MM games came out really often and quickly, games normally have a dev time of 2 years maybe more but MM games were made in a year maybe less in the classic/X cases, and when Capcom slowed down production to a few games the series started becoming unprofitable....they should've innovated sooner and not release the same cash-ins although BN/SF as well as Zero/ZX were very unique and creative shame they were handhelds.)
Resident Evil is their highest selling IP.
Monster Hunter is their highest selling IP in Japan (even reaching near SF sales worldwide, it may have even surpassed Onimusha and DMC in total sales...although MH had more games than DMC and Onimusha).
Street Fighter is Street Fighter...who cares.
Devil May Cry was selling good (their fifth franchise to pass the 10 mil units mark) but if Capcom continues with DmC, they might as well be digging the DMC series grave.