If you had to choose, which would it be? You don't have to preface it saying neither, because obviously no one wants to be deaf or blind (okay, actually some of the Deaf community are happy they are deaf, but that's opening up another can of worms...)
I'd probably choose deaf, myself. Music and singing is such an important thing to me, but I feel like you retain a lot more independence when you're deaf. Most deaf people have normal lives, they just can't hear. Whereas, when you're blind you can't drive, have a harder time getting around, you'd have to relearn how to read, writing and video games are pretty much out of the question...
So yeah, I'd choose deaf.