Going with the opposite idea of the "worst sci-fi ever" thread, here is a thread where everyone should recommend GOOD sci-fi that not everyone might know about. Obscure Sci-Fi if you will... with that in mind I present to the masses my pick for really good Sci-Fi flick that didn't get much recognition:
Enemies because they were taught to be. Allies because they had to be. Brothers because they dared to be.
Starring Dennis Quaid and Louis Gosset Jr. as two star fighter pilots from different warring planets who crash land on a barren planet together.
now you go.