If I was ONLY after a Kudu, my choice of cartridge would likely be 7x64, or .308, or .30R Blaser. Not that those choices are any better than many others, they're just what I like and have, and will work perfectly fine.
If I was also hunting in a dangerous game area, or hunting dangerous game at the same time, I'd likely choose my 9.3x62, or 9.3x74R or .375H&H. Just because you never know what's around the next bend in the river valley, or behind the next bush.
I've taken only two Kudu, one with a rented .30-06 and one with my trusty 9.3x62. When in Lion or Buffalo country, carrying the 9.3 gives me more peace of mind.