Once Pac gets going he trains harder but Mayweather can train more often because he is more focused when he's not in training.
Both stay in shape between fights (Pac not so much anymore for obvious reasons). FMJ trains the same all year long, Pac plays tons of basketball when he's not in training camp. So, Floyd = more consistent, Manny = more intensity.
For me it's Mayweather. Mayweather NEVER stops working in the gym. Where as Pacquaio is so damn busy nowadays, he has no choice but to make the gym #2 on his list at times.