I'm also wondering wich one to start with... If it's not already too late :p
But i'll go with the GPU mining, kinda for the same reasons you mentionned, the hardware is still worth something separetly if i decide to stop.
I'm planning on a 1500$ investment for 4GPU mining rig, and i'll see where this will go. I wanted to start with 6 GPU but dont want to spend too much in this uncertainty..