Lots of options is always good. However if your interest is the stalking / hunting bit, and rifle really just a means to an end, then a good all rounder has to be a cartridge for which you can find ammo pretty much anywhere that you are likely to find yourself. In the UK that really means a 243, 308, 270 or 6.5x55 or CM.
For those of us, you and me included, who really like their rifles, and hand load then something more exotic is definitely the way to go.
Personally I would like something a little bigger than a 6.5, but given a good bullet I doubt anything that walks will have any different reaction to a well placed bullet. The likes of Bell showed this very well on large African game over a hundred years ago with the 6.5MS, 7x57, 303 and 30-06. Choice of shot placement and bullet construction as always is critical.