Before I recommend anything, you should know that my taste in hip hop is focused on the style/styles of hip hop that was popular in the late 80s and 90s and was developed on the east coast. On wikipedia the time period is called "the golden age of hip hop", I know it sounds pretentious but that's what it's called if you want to delve deeper into the music.
Another vote for
Gang Starr. Their albums
Hard to Earn and
Moment of Truth are their best work imo.
You Know My Steez is a personal favourite.
Jeru the Damaja made two classic albums in the 90s called
The Sun Rises in the East and
Wrath of the Math. Two tracks on the first album are
Come Clean and
Can't Stop the Prophet.
Pete Rock and C.L. Smooths first album
Mecca and the Soul Brother is worth giving a try. On this album you will find a song that time and again has been called one of the very best hip hop songs that has ever been made, it's called
They Reminisce Over You (T.R.O.Y.).
Black Sheeps first album
A Wolf in Sheep's Clothing. Their biggest hit
The Choice is Yours is on this album.
Last but not least I recommend
Eric B and Rakim. Pretty much their entire discography. This is just some tracks that I like from their albums:
Paid in Full,
I Ain't No Joke,
Microphone Fiend,
Don't Sweat the Technique,
Juice (Know the Ledge).