I'd say it depends largely on the architectural layout. Typically, if I have the freedom I prefer the two-story x-brace as it doesn't require as many bays as single diagonals would and eliminates the issue with unbalanced forces that happen with chevron or v-bracing.
A single diagonal brace has it's merits, but also it's limitations. In high seismic areas you need to have tension diagonals balancing your compression diagonals or else you have to design the brace for the overstrength factors. Once you design the brace for the overstrength factor this essentially eliminates your redundancy in the design as your collectors, etc. will no longer have amplified forces as compared to your brace.