Star Wars is my only priority. I'd never have started collecting 12" at all if SS hadn't started that. But I'm no completist, and there's a lot more out there.
So far LOTR, the future Indy line, and Hot Toys POTC have my attention. Those are the only ones I can see myself expanding beyond a few figures. Unless someone starts a Spaghetti Western line, or some kind of samurai cinema line. My holy grail would be a good Ogami Itto figure. Or the Lone Ranger.
Otherwise, if someone makes a cool figure outside of all that, I'm game. I ended up with the Medicom Evangelion ladies, and the Kerberos figure (scariest cop I ever seen). Azone's Saber figure with the metal armor is pretty tempting too, but she's some expensive. If they made a Rider figure, the price would be more palatable. I'd also really like it if Medicom did Inuyasha figures. The world needs a 1:6 Sango.