I think most of fuzz or heavy distortion sounds quite lame. Especially with high pitch screaming. I remember when I first time heard deathpile split LP with Discordance, and first impression of flanger + distortion scream didn't make me think of robots, but little sheep! haha... Perhaps also because it was so up front. I don't care much of the *really* cheesy robot effect. but tasteful use of all those normal electronic effects as chorus, phaser etc work for me well. It's matter of finding settings that contribute overall feel of song and blend vocals into atmosphere.
I think main thing is not that vocals are clean narration on top of totally "unrelated" electronic sound, but ability to make vocals be also interesting sound element, besides the delivery of words. Certainly not always happening...
I've found that best way to distort vocals would be simply good type of overdrive. And often better results than any pedals, are things like analogue tape recorder input gain. You get raw and ripping overdrive, but not overall distortion what would make it flat. 4-track recorders, tape decks with microphone inputs, various kind of other recorders. And like GEWALTMONOPOL mentions, very good vocal distortion (and overall tone on frequencies) can be achieved with taking vocals through synth. MS-10, MS-20.. endless possibilities on latter one. Also good to filter many kinds of noise.
