Take the two big ones because that's what you got them for
My vote would be for the 375. But, nothing wrong with the 7mm for any plains game. I was amazed at how many times I saw guides and rangers carrying a 270win as their "Do-All" rifle.
And yes, I know some countries often have minimum calibre restrictions for dangerous game but there seems to be a fair bit of leeway on using lighter cartridges even for the big animals. And, seeing so many 270s in Africa speaks volumes for the cartridge's performance.
take the two big ones because that's what you got them for