As you can tell, I am a .250-3000 fan. I am a big fan of the 75 gr. V-Max bullet. It has proven extremely accurate in several 250s.
I find the .243 Win. boring, for no obvious reason. I recommend the .243 to shooters who don't reload, but reloaders usually find the .250 Sav. to be very enjoyable to work with.
I gave my only .243 Win. to a nephew who doesn't reload (yet).
The .243 caliber rifle that I do own and enjoy is the better one, the 6x57, thank you very much.