The 70s were certainly an exciting time to be a Batman fan (hence my "bronze-Age Batfan" site, embryonic though it is:
http://batfan.superman.nu), what with Neal Adams, Irv Novick and Jim Aparo art all over the place, creepy-cool stories by Denny O'Neil, Frank Robbins and others, genuine, bona-fide mystery stories by writers like David V. Reed, those far-out, weirdo tales by Bob Haney over in Brave and the Bold, and finishing off with the stellar "Detective" run by Englehart and Rogers in '78 or so.
I love the output of the 40s and 50s (the latter of which wasn't really all Sci-Fi; just the stuff featured on the covers), I'm so-so about the 60s (love the TV show but didn't much care for silly junk like the "Outsider" saga), but my vote has to go to the 70s. This was a period where Batman managed to be creepy but not gruesome, formidable but not omnipotent, serious but not a jerk, and above all a hero...not a nutjob. Modern writers are so sure they've got Bats all figured out by playing up this "vengeance-crazed" portrayal; they think this approach is more sophisticated and "realistic." What it really does is emasculate the character. It casts Bruce Wayne as the eternal victim, forever unable to overcome the childhood tragedy that poisons his mind and renders relationships and personal growth impossible. In the modern books, the bad guys have already won, because they've destroyed Batman from the inside. In the 70s, Batman did what he did because it was the right thing to do and he could do it better than anyone else. He was a hero who turned a tragedy into something positive.
But picking the 70s is also cheating a bit, because in the 70s I had re-runs of the 60s TV show every day after school, and those wonderful 100-Page Super-Spectaculars that always included stories from every decade. The 70s gave young fans like me easy access to Batman's entire history, and I learned to love it all.