Welcome to the forum. Either calibre would be a good choice.
I have been hunting with a Chapuis 9,3x74R for a little over 5 years. I have 2 scopes fitted for it, a Leupold 2.5x8 with heavy duplex and recently added a Swarovski 1.75x6 with the illuminated circle dot reticle for my lion and leopard hunt this June. I have used this and my other big bore doubles for almost all of my hunting for 6 years.
The Chapuis only weighs 7 1/4 lbs without the scope. It is on a smaller frame than the Krieghoff. I have taken it on true backback hunts for Bear in Montana. I have been very happy with it. I do consider the 9,3 [and the 375 Flanged or H&H] to be light but useable on Buff. After you use your medium bore double you will probably want a big bore double too.

One thing nice about the Krieghoff is that you can get multible barrels fitted to one frame. A Krieghoff with 2 barrels, one in 9,3x74R the other in 500/416 [both fitted with scope] would be a hard combination to beat.

I recently shot a Krieghoff 500/416 and it was very accurate and the recoil was not bad.
Still the Chapuis is a lot lighter and slimmer rifle.
2 Chapuis doubles a 9,3 and a 470 [with an extra set of 12 ga. bbls] would be a very good combo.