This is my list. Influence and innovation for their time will be a factor, although the quality of the lyrics, verbal dexterity, delivery and overall sound will be the main criteria. Here's my top 50, and it can definitely stand some revising (I just drew it up quick)
- Enter the Wu-Tang (Wu-Tang Clan)
- Illmatic (Nas)
- The Score (The Fugees)
- The Eminem Show (Eminem)
- Life After Death (Notorious BIG)
- Capital Punishment (Big Punisher)
- Good Kidd Maad City (Kendrick Lamar)
- Only Built 4 Cuban Linx (Raekwon)
- My Beautiful Dark Twisted Fantasy (Kanye West)
- Liquid Swords (GZA)
- Black on Both Sides (Mos Def)
- The Black Album (Jay-Z)
- All Eyez on Me (Tupac)
- Life After Death (Notorious BIG)
- Reasonable Doubt (Jay-Z)
- The Marshall Mathers LP (Eminem)
- Me Against the World (Tupac)
- The Diary (Scarface)
- To Pimp A Butterfly (Kendrick Lamar)
- Death Certificate (Ice Cube)
- Aquemini (Outkast)
- Ridin' Dirty (UGK)
- Graduation (Kanye West)
- It Takes A Nation of Millions (Public Enemy)
- The College Dropout (Kanye West)
- The Chronic (Dr. Dre)
- 2001 (Dr. Dre)
- Do You Want More? (The Roots)
- The Fix (Scarface)
- ATLiens (Outkast)
- Take Care (Drake)
- Late Registration (Kanye West)
- Paid in Full (Rakim)
- Don Killuminati (Tupac)
- Supreme Clientele (Ghostface Killah)
- The Blueprint (Jay-Z)
- The Slim Shady LP (Eminem)
- Straight Outta Compton (NWA)
- Tha Carter II (Lil Wayne)
- The Low End Theory (Tribe Called Quest)
- Long Live the Kane (Big Daddy Kane)
- Iron Man (Ghostface Killah)
- Doe or Die (AZ)
- Things Fall Apart (The Roots)
- Internal Affairs (Pharoahe Monche)
- Stankonia (Outkast)
- Black Star (Talib Kweli & Mos Def)
- The Miseducation (Lauryn Hill)
- Fear of a Black Planet (Public Enemy)
- License to Ill (Beastie Boys)