I basically have no sense of smell so its easy for me, but it doesnt bother me.
Also for everyone saying touch, have fun. Pain is a good thing, let's you know when you're damaging your body. Those without the sense of touch end up biting their tounges and the inside of their cheeks constantly (hope you like the taste of blood) and also end up having many infections causing them serious problems, pancarese (sp?) is the main one, end's up swelling up and can burst before being removed. It then infects the blood steam and the rest of the body. Any small cut will be ignored (cant feel it obviously) and can become infected, which in turn will be ignored. I saw a documentary on this, and a little girl had burnt all the skin off her tounge after drinking hot chocolate. She was so young the parents didn't realise she didnt have a sense of touch, and yeh, lots of blood...
In the end, instead of becoming a superhero, you end up dying from any little infection.
So yeh, I'd go with taste or smell, leaning towards smell.