You wake up tomorrow and discover you are either blind or deaf.
Argument for losing sight -
You would have the memories of what things look liked, color and descriptions would make sense and you would be able to follow conversations easily. You could learn braille to read and have devices to read to you.
Argument against losing sight -
You would not really have any idea of what was in the room with you. Fear would probably be more common as you can't see the unknown. You would have to rely on others for many things. You would have to learn how to detect emotion through sound. You would never get to see anything new (art, movies, pictures etc). You will never see your children/grandchildren grow up, get married etc.
Argument for losing hearing -
You could see everything around you and you could learn lip reading etc. You know what things sound like so you as you are watching things, memories of sound will help follow along. Visual cues can tell you things that hearing can not tell you.
Argument against losing hearing -
You could not hear what was going on around you if you were not directly facing it. Communication with others may be hard since you will need line of sight to read lips. The silence will drive you crazy since you are not used to it. You would never hear your grand kids speak. You would never hear any new music.