Lavender is always a top seller for me, and right now my other best sellers are; Zen, which is a proprietary blend of mine with about 12 EO's, Flowering, another proprietary blend of about 7 EO's, Awaken, a 4 EO blend, and Herbed Cirtus, a FO/EO blend.
But the top sellers change with the season, with the year, shoot, sometimes with the day even. It does tend to cycle though. For more than the last decade though, Lavender has been my number one seller in all my products. Sometimes other scents will tie or come close, but nothing has ever knocked it out of the top spot.