Zeiss, with it no need to go with 50mm bell. Ihave 2 40 & 44 and don't notice any real world difference between them. In my comparison both favored better than the VXIII in regards to clarity & brightness. Constant eye relief is big plus IMHO. Never owned a scope with it prior and now I really prefer it to the variable my leupolds, bushnells, etc give.

Either scope (leuy VX III or Conquest)in 40mm will harness/transmit more thanenough light for legal biggame hunting.

If you must have a 50 mm then so be it, I still say Zeiss though.