Gert, my experiences. I have used 235, 250 and 300 grain bullets. I wont waist my time using 235s again (lions, warthog, blesbok, gemsbok, springbuck, blue wildebeest). 250 Barnes TTSX performed excellent for me on croc at 95 yards, eland at 125 yards (front quartering shot breaking front right shoulder and ended up under the skin on the opposite side), black wildebeest at 170+ yards, sable at about 25 yards and warthog at about 75 yards. A caracal at maybe 30 yards. The 250 performed well, but only recovered the one from the eland. The BC is much better on the 250 and longer bullets thus shooting flatter at longer ranges in my experience.
That said, I much prefer the 300 grain now. It is easier to get a soft 300 grain to shoot to the same point of impact as a tough 300 grain. Example: the 300 Sierra and the 300 A-frame. All you have to do is change bullets depending on the game as opposed to change scopes or scope settings when changing bullet weights.
In short, I recommend just go with a good versatile 300 grain bullet, ie, Rhino, TBBC, Northfork, A-frame, etc. If you’re not planning on a thick skinned DG (buffalo), the Nosler Partition at 375 H&H velocities is pretty good and should handle up to eland on a heart/lung shot.
Best of luck with what ever you choose to go with!