The ones I always buy again when I run out include:

VO5 Hot Oil treatments
Oil of Olay Regenerating serum
DHC Cleansing Oil
Lancome Bifacils
MAC Fluidline Eyeliner
MAC Lingering Eyebrow pencil
L'Oreal Voluminous Mascara (love diorshow and lancome too but they're too pricey now that I rarely wear makeup)
Cle de Peau concealer

What are some of the products you always buy again once you run out?