SOUNDWAVE
Summary: Soundwave: Superior.
In longer form: In IDW1, Soundwave can't process his sensory input and lives in a constant state of overload until he is adopted and coached by Ravage and Laserbeak. In IDW2, Soundwave's speech bubbles have a jagged, monospace, robotic style that those of other Cybertronian characters do not. In TFPrime, he communicates by glyphs, remixing audio, and, in absolute extremis, one (1) line in the Cybertronian equivalent of mouthspeech, as Ratchet talks about taking him apart to see how he works, because he is different: "Soundwave: superior. Autobots: inferior." That mouthspeech equivalent, unlike other Cybertronians in the show, has two layers audible, rather than them being smoothly mixed. Also, by displaying glyphs on his screen, since he is a device, he is using an AAC device! Soundwave: possesses speech disability. Webmaster, Braigwen: does, also. Therefore; Soundwave: beloved.
Soundwave: representation! 
I also really like how he's a political idealist and dogmatist; while it's not his most heroic trait, it also... isn't not?
My personal interpretation of his voice is that it sounds like a vocoder, while most Cybertronians can generate much more complex synthesized speech. I think his wiring is so shaped around dealing with the sheer volume of input he recieves that vocal output is an afterthought for his frame and his processor alike.
