When I was a child I went totally crazy with E.T. and Tron. :-)
E.T.: I kid movie really inspired I would say. It has its points. When everyone was crazy with aliens coming down to kick human asses, E.T. just switched the p.o.w. by 180°, huh? Also, it's a movie about solitude and emotional communication in infancy. Definitely worth seeing.
Tron: alas, "do you have faith in users" is such powerful a line that just blown the shit out the whole Matrix dumbness. I was amazed to think that our "level" of reality may just be a level in the middle in a whole wide array of realities. Ok, I was like 6 or 7. Not an epiphany, but pretty impressed. :-)
In early adolescence years I've got hooked to Back to the Future, for I was really into time traveling. And aliens, of course, thus I loved Close Encounters of the Third Kind as well. This one maybe does not strictly count as a kid movie, right?
Distopic future was also my thing, so yet, Terminator and Terminator2 I loved also, but not as much as RoboCop. RoboCop had this 'realistic' ring to it that really made it into a classic beyond usual SF flicks imho.
Oh, and the other thing I was crazy about was the idea of mystical old artifacts, so yes, Indy was my friend.
Than 'Fushigi no Umi no Nadia' came linking all my narrative fetishes and heh, I was done.