I generally don't do artificial flavourings.
Lemon. Some lemon juice in that salad, some grated lemon zest on that pasta dish etc. etc. etc. are MAGIC.
My favourite natural flavour would have to be vanilla. It's also the only flavour enhancer that seems to make dogs go wild, their genitals well flushed and their heads nice and hot. I like dogs cuddly and hot. Only use all natural, no sugars, no artificial stuff that harms or kills your dog; start small. End up howling with the pack.
Strawberries with a sprinkle of sugar to draw out juice, with some lemon balm and freshly ground black pepper added when the sugar is wet. Extremely satisfying flavour and smell when using proper, fresh ingredients. No substitutes.
Chocolate. In all approximative pure forms and mixed with milk or cream.
Epoisses, Taleggio and the like... cold or heated, with some good bread... and maybe a glass or two of wine. Heaven on earth. Flavour that lingers yet shifts after every bite. Add some nuts, dried fruit (Turkish peach!) and/or olives for extra enjoyment and complexity.
Bacon. Just plain bacon is what makes being human special. Also goes extremely well when enhancing Kosher and Halal dishes. Gives them more depth and complexity. When using in hummus, you might want to switch lemon juice with some white or red wine vinegar.
Man, now I'm hungry.