It's well known that scent is the strongest tie to memory, out of all our senses the sense of smell has incredible powers. That is also mainly how we pick our favorite fragrances. A particular fragrance can remind you of that one summer morning, the fresh summer breeze, the endless flowers in a garden or the delicious taste of a fruit. You pick your fragrance according to your favorite memory. I guess that is why I don't believe in a signature scent. It's great that you have a perfume that you will always adore, keep it in stock. However, don't limit yourself, because you might miss out on some great fragrances. You should have one for each of your moods, when you are feeling feminine (flowers) or want to feel fresh (citrus).
A scent is very personal, very unique to you. The reason is that a fragrance reacts with your body's chemistry to create your scent. That is why you want to always test the fragrance on your skin, to see how the scent will develop. If you smell it on a tester or ask someone about that fragrance you might end up not liking the fragrance. The first reason is, the tester has no additional chemistry therefore you will smell the fragrance in pure form. The second reason, just because it smells great on someone else it doesn't mean on you it will smell the same. That is why taking your time and testing the fragrances properly is the best way of making sure you will pick one that you will love.