As far as pioneers of using computers in music or electronic music then I'd have to say Kraftwerk, Delia Derbyshire, Gary Numan, Jeff Wayne(War of the worlds). I'd say these people had great vision & saw the worth in using computers in music, they took some of the first steps.

As for people having a the greatest inpact on electronic music, its completely subjective & down to personal view. I personally think a city has had the most impact, Detroit.