A rather thought provoking situation ... even if it is only hypothetical.
As a professional musician, the thought of either situation happening is absolutely dreadful. Not being able to hear myself or others play the grandest of all instruments (the pipe organ) is a frightening thought. And, without sight, not being able to see these grand instruments and the world around me ... and not being able to drive anymore ... is troublesome, too.
If I had to pick one, I guess I would choose deafness. I've already heard many of the great organs of the world, and played a few, too. But for me, I value my sight over hearing - being able to see family, scenery and being able to communicate with others on fora like this one.
I suppose if I had been blind at an early age I could have coped with it ... Jean Langlais did, and became a very successful organist/composer. We don't hear too often about deaf organists.
Well, those are my thoughts, anyway.