This is an evolving topic. Would like to get your opinions on this.
Atmel, ARM, Intel main processors what do you think ????
If you were designing a board what would you go with ?

Could you just use a rasberry pi 3b+? There's a few good open source programs and there should be more than enough hardware for it. The inbuilt wireless is a nice touch. Most reprap boards are arduino variants. Not much firepower and customization in them though.
Yes theoretically I can see no reason why you could not use an RPI3. You could have wifi remote access, cmos high definition cameras as well as normal motor control. Sounds like a good idea.