My first was Aquadisiac e/s. It was not what really hooked me, in fact you can say I didn't get hooked for almost a year. I had some eyeshadows but if I bought makeup, it was mainly Lancome, Urban Decay, or wherever the GWP was. What really got me hooked was going into a freestanding one day and asking about pigments and the girl did a look on me with them. That and Fafi (not the Fafi collection itself, since I hated most of it, but the packaging) were what really suckered me in.
As for my can't live withouts...Northern Lights and Glissage MSF's, Port Red l/s, Crystal Avalanche e/s, Belightful IPP, Beautiful Iris e/s, and Helium pigment. That's just a small list.