Best would have to be the 300Gr Nosler Partition, but Nosler unfortunately hasn’t manufactured new consignments of these ever since the outbreak of the Chinese virus. Fortunately, I got very lucky & managed to buy a couple of boxes from a gun show in Nevada.
Another excellent lion bullet from the days of my youth, would have to be the old copper jacketed lead cored Barnes Originals (with the 0.32” thick jackets, not the 0.49” ones). Unfortunately, Barnes no longer offers these in .375 caliber.
Among currently manufactured bullets, I would consider the very best to be the:
1) Wim Degol Lion Bullet
2) North Fork Percussion Point
If limited to factory loads, the Federal Power Shok 300Gr soft point gets my vote. Be warned however, that the bullets WILL break upon when striking the shoulder bone/scapula of a large make lion.
Over the years, I have hunted my first few lions with the old RWS 300Gr Kegel Spitze cone point factory load (now unfortunately discontinued). I shifted to Nosler Partitions in the 1990s and I currently employ the Federal Power Shok.
If I had anybody who would load me up some ammunition with 300Gr Wim Degol Lion bullets, then that would be my top choice (I don’t possess a lot of confidence in my skills as a hand loader to load my own dangerous game ammunition).