I would suggest: Xperia ZP.
Spec-wise, it would have:
-Snapdragon 600 with Adreno 320 GPU.
-2GBs of RAM (1.5GBs sounds more logical though)
-13mpx camera with flash, 1Mpx front camera (or 8mpx rear camera as long as it's as high quality as the one on Xperia P)
-4.6" HD IPS screen
For the design, I would like something between Xperia P (which I love) and Z1 compact, so it would be a minimalistic phone made mostly out of aluminum, but with the shape of the Z1 compact. Also, why not make it water-proof? As it seems to be the trend nowadays.
Anyways, share your thoughts. Remember, keep it real! (That means no 4K displays, 3GBs of RAM or Snapdragon 805 >_> ).