Let's Make Robots!

tablet

What "Brain" should I chose for my robot?

I am considering a more advanced  "brain" for my Service Droid robot. I know I could use the computer to do all the advanced computing and relay commands to the robot, but if possible, I would like to have an integrated system. So far, I see 3 variants:

1. Raspberry Pi + webcam (+ screen?)
2. Android phone with integrated front camera
3. Android tablet (4.3" screen) + OTG adapter + webcam