The best I have found for general purpose with the P-01 has been the GECO (Dynamit Nobel) 124 gr. FMJ. This appears to have dried up somewhat, but individual sellers still have it (gun dealers, gun show vendors, etc.). Next would be the Federal American Eagle 124 gr. FMJ.
In defensive loads, the 124 gr. Speer Gold Dots or 124 gr. Remington Golden Sabers perform quite well. These are 9mm +P loadings, which the P-01 can shoot all day.
I shoot reloaded ammunition in the P-01 all of the time, but they are my own handloads. Most duplicate the GECO loading above (124 gr. FMJ at @1,175 fps, with Nobel SP-8 powder). The main reason not to carry reloaded ammunition is because of the fact that commercial ammunition has sealed primers and casemouths, whereas virtually no handloaders go this extra mile. (I know I don't.)
As you can see, I favor the 124 gr. weight, but in my testing, so do most CZs!