Nice mech! For my comic I used a mix of MS Paint (!), FXHome Effects Lab Pro (Expensive!) Adobe Photoshop (Not as much, but still Expensive!). They are all expensive software (Yes YOU Ms Paint!) but the output is fantastic!
The shape looks really outta whack compared to you other mechas. Work on this. PS: I just edited my Guyver, and I'm gonna post new pics tomorrow. It actually has a neck and a more Guyver-ish torso! It'll stay on the same page though.