Solid year. These were my favorite albums:
Kanye- College Dropout
Cee Lo Green- Cee Lo Green Is... The Soul Machine
Royce Da 5'9"- Death Is Certain
Lloyd Banks- The Hunger For More
The Roots- Tipping Point
Crunk Juice, Urban Legend, Straight Outta Cashville, Twista's Kamikaze, Ball & G's Living Legends, and Mobb Deep's Amerikaz Nightmare also got considerable play.
As far as R&B, it was the debut of John Legend. That album seemed to come out of nowhere. It was pushed back several times and it seemed like he disappeared after "Used To Love You", then boom the album came out. Alicia was still killin' with Diary of Alicia Keys, and Usher owned 2004 with Confessions. Mario also dropped his best song in "Let Me Love You".