Other: Why compromise when you can have it all?
I'm also pretty sure Krochus wants a cartridge which will shoot a 125 gr bullet at 2300-2400 fps, which is excellent for antipersonnel and medium sized deer out to 150 yards or so.
.338 whisper is useful only for getting the most energy while remaining subsonic. In terms of energy, period, all the .221 based cases are equal with equal bullet weights, as .300/221 is quite capable of shooting a 240 grain bullet at 1400 or so FPS.