I have burned many candles, scented and unscented. I quickly didn't see the point of burning unscented candles as all they really do is take away the oxygen in the room. But scented candles are not only aromatic, they come in all kinds of colors, shapes and sizes. A candle will burn quicker when thin, and upright. Candles that are thick and have an odd form will definitely take more time to burn. Meanwhile, the candles that come in a long tall glass container will take the longest time to burn.
The fragrance didn't seem to affect the way the candle burned or how long it took to burn it..