Another vote for the Gorn captain. It's just such an iconic design (TOS and Enterprise really had the best aliens) and playmates made a fun figure out of it. I especially love the fact that he can move his legs, despite wearing a... skirt...thingy. They just sculpted it as a part of his legs. I wish they would have done the same for all the other Skirt-Figures (Uhura, Kes, etc).
I also love Picard in his jacket and TNG-Data. Data has a special place in my heart, for he was my favorite character and my first star trek figure.