Naughty by Nature, their eponymous 1991 release with OPP and Everything's Gonna Be Alright
Agree with Tone Loc's Loced After dark.
Does Rage Against The Machine count? I like all of theirs. (Can't believe it's 20 years ago!)
The Chronic has already been mentioned, as was Straight Outta Compton.
I liked Us3's Cantaloop.
I am going to include some trip hop - so Morcheeba and Massive Attack get a tangential inclusion!
The best single rap tune of all time is Tupac and Dre's "California Love." No arguing!