It was most fun Killing Sanctus on mission 11 and 20 because it was SO MUCH FUN to see Nero in DT and buster him and The She-Viper (Echidna) all 3 times, esp. becoz of the way she helplessly shrieked. The frogs wer a bit annoyig. Agnus was cheap because he took away your health. Probably the most annoying boss was the Savior.......very tiresome batle, and not fun at all. Jumping about was irritating and the faults made it worse...
The best boss was probably Credo because the fight had a real epic feel to it, with the while round arena and everything. Dante was difficult to kill, but I really don't see him as a boss in this one.