As the obvious ones have been said, in the spirit of the OP looking for hidden gems:
Check out Flick of the Switch. Much underrated and with some great sounds. Much rawer than BiB. Self produced, wasn't it?
Also Stiff Upper Lip, was, IMO, a return to form, with a great blues-club feel to it. Quite laid back, and with better (if simpler) set of songs.
Don't forget Who Made Who for some instrumentals. Also 74 Jailbreak and...oh, anything really.
BTW, if the guy asked for your favourite albums, how negative is it to chime in with the album you don't like? What's the point dude?
