I'd prefer to lose sight rather than hearing or speech, and I definitely agree with those for whom hearing is the most important of the three. I have very often heard people express an opinion that losing their sight would be the worst thing for them. I wonder how many of them have actually thought about how, in Helen Keller's words, being deaf "separates us from people" (thanks, Brandon). Losing communication with the people around me would be the worst thing for me.