You can choose:
-sight
-smell
-hear
-feel
-taste
and why?

I think smell.
I would hate to not hear or see as that's such a huge part of life. Feel is pretty important too i think. I'd feel lost if I couldn't feel what I was touching or grabbing for.
Taste is wonderful, although without it we could just eat a bowl of every type of veg every night, be healthy and not feel deprived as we couldn't taste chocolate and other stuff anymore. I'd be so much healthier, but I really do enjoy my treats.

Healthier, but boring.
So that leaves smell. I don't really enjoy that many smells and the only danger of losing smell is of the warning sign for fire.
So, just make sure you keep on top of your showers, for the sake of other ppl's sense of smell.