A SEPIC is similar to a traditional buck-boost converter, but has advantages of having non-inverted output (the output voltage is of the same polarity as the input voltage) while in case of buck-boost the output voltage is of opposite polarity with respect to the input voltage.
SEPIC converter has the advantage to romove the unwanted noise through capacitor. and it give +ve output voltage. And one more advantage is it can be used as isolation dc/dc converter.