The sense of smell differs from the other major senses in that it is more primitive, working more directly with that part of the brain which is 'older', in an evolutionary sense, than the rest of brain.

There are three levels of choosing incense: 1) How it smells before burning,  2) while it is burning and 3) after the fragrance is done.  You can be attracted to various scents during any of these steps.  

As you personally change, the incenses you like may also change.  When I say 'change', I am speaking of any change in your life.  Have you changed your diet?  Are you in a new relationship?  Did you get a new job?  Or how about a new pet?