Oh man....it's hard to choose even one. I mean so many I feel like it would be drastic to live without. My eyesight isn't the best and I fear ever losing that. Same with hearing. I love just how great my hearing is (seriously it's like a curse at times too. People can't listen to music too loud here xD). I love being able to taste and smell. Touch is kind of important too. I guess taste, because one. You can eat anything and not care if it tastes bad or not. A veggie hater could suddenly eat healthy lol. It's kinda of something to be careful of too though. You couldn't just go eating tons of ghost peppers. That'd be dangerous. So I guess the best would be taste, but good smells would be pretty taunting.