You can cremate me to the Straightener
Damn this rules
Lifelong Black Sabbath scholar here, oh man do I have an overzealous list
For the early days, I'd say a hard tie between Evil Woman and NIB. The demo reel of the unreleased song "When I Came Down" is also essential
For the mid 70s I'd say Under The Sun (the anthem of my teenage days) & Into The Void (which Bill Ward astutely called the true climax of the band).
For the late 70s I'd say Junior's Eyes (a fucking marvelous song... if you ever want proof of how brilliant Ozzy is at what he does, listen to the version with Dave Walker when he was briefly lead singer before NSD came out) with a very honorable mention to You Won't Change Me because Of Course.
Dio era part 1 is not my fondest Sabbath era (I say part 1 because Dio era part 2 with '92's Dehumanizer L.P. is fucking TOPS), but I have to give mention to how spectacular of a song Heaven & Hell is - BUT the real star of the RJD debut for me is Lonely Is The Word.
NOW for arguably the most hidden gem of the Sabbath catalogue: BORN AGAIN! To be honest this entire album is my favorite song from this album. It's an acquired taste (mix-wise at least) I do admit that ..... but god damn it's so COOL. For a taste, I'd recommend Keep It Warm & Disturbing The Priest. Once you get your toes wet, blast Zero The Hero.
I won't comment on the Ray Gillen era because it never came to fruition (that's a long story...... fuck Ray Gillen), BUT I will say that for Glenn Hughes brief tenure No Stranger To Love is a fucking HIT. I could go on for ages about that power ballad ...... BUT we have more to address and I've already gone on for way too long.
NOW for the icing on the cake: the Tony Martin era! God damn if the IRS albums aren't the tits. Eternal Idol is a fabulous debut. ANCIENT WARRIOR! And of course, Headless Cross is fucking stellar. Devil & Daughter? The title track? Fucking GOOD shit. Feels Good To Me, Sabbath Stones are some decent tracks off TYR. AND WHO COULD FORGET, the Ernie C. produced L.P. FORBIDDEN, so fucking cool. Illusion Of Power is forever a hit.
I mean I've already gone on for way too long but as you can tell I have Three Many favorite Sabbath songs, and I can never pick an era because I love them all.
But, purely in terms of what defined my teenage years: it was of course the Ozzy Era and SBS was my favorite L.P.
At that time, my absolute favorite song was Spiral Architect