I'm working on a new version based on the experience I made with the previous versions.
The plan is to use stepper motors and timing belt gears.
The plan is to use a Nema23 stepper for the rotary base,
Joint one and two will be Nema24 ( this: http://www.omc-stepperonline.com/dual-shaft-cnc-stepper-motor-nema-24-100mm-4nm566-ozin-24hs393008d-p-388.html )
Joint 3 and 4 Regular Nema17 stepper and for the 5 joint a HerkuleX DRS-0101 .
But nothing is final now.
Power supply will be 24V-36V I guess.