Unfortunately, due to a botched surgery I have almost no ability to taste or smell anymore. However, my two favorite smells are chocolate mint ice cream (yes, the smell is distinct from just chocolate or mint) and gasoline.
I'm sure there are at least a handful of people curious about the weird combo.
My love of mint chocolate ice cream, including the smell, is from one of the few positive memories of my grandmother before she was struck with dementia and became.. someone else entirely. She looked after me and my siblings fairly regularly and kept us close. One of our regular routines was being with her when she visited the local pharmacy, which had a storefront that included an in-house ice cream parlor. Whenever we would go, I'd order mint chocolate cream ice cream. It's a shared memory with my mother sharing a sip of a grasshopper (cocktail) with me beforehand. My mother letting me try a taste of her drink let me know I enjoyed the flavor, and the ritual with my grandmother cemented the love of it and the memory/memories.
My love of the smell of gasoline isn't tied to any particular memory, but my father was a mechanic and I've just always attributed that to the amazing man that made me who I am. Every time I pump gas, a little part of my brain travels back to those days spent with my old man in the garage.