I don't have just one favorite, and complex combinations of scents appeal to me. I made soap with essential oils for a while and helped friends mix their own perfume based on what they liked.
Now the BEST thing I ever smelled was when one of my boyfriends came over, we had sex, I went to the bathroom, and when I walked back into my room and the scent of whatever essential oils I had recently used lingering in the air combined with the smells of sex . . . OMG, that was heaven!
Sex smells on their own are pretty gross, but when combined with other things, wow! I think our ancestors found the scents of sex more enjoyable back when they lived in forests and had sex in meadows with lots of flowers around.
Does anyone remember the Magic School Bus episode where they make a perfume and toss in a used gym sock?