Start with any of the mood Muzik series. My personal favorites are Mood Muzik 2 can it get any worse, and Mood Muzik 4 a turn for the worst. Also Padded Room is okay. It is good lyricism on the album, but it has a lot of week beats on it. BTW if you haven't heard 10 minutes make sure you hear that.
Also check out some of his battles with Game and Saigon.
Also, you gotta put his music in context, because he was doing this for 10 years.
Early stuff 2003, punchlines and he was essentially a mixtape rapper. Album had some substance and he was doing some pain rap/introspective rap.
2004 First Mood Muzik, also running with Desert Storm, still haven't came into his own, he didn't even have a movement at this point.
2006, Mood Muzik 2, he was very frustrated with his circumstances, you can tell he was rapping like his life depended on it. This tape set off his movement.
2008, he regrouped, got focused, dropped Mood Muzik 3, and a lot of good songs and freestyles along the way.
By 2008, he has at least 200+ tracks floating around. I followed him since the beginning, I got all the music as it dropped. He reinvented himself 3 times. It can't better than this, right?
Halfway House, Escape Route, and Padded Room feel like he was going through a transition period, music felt real trippy and dark, I felt he was being too abstract. The outcome was good, but...then he was back to work.
2009 - is the Joe Budden you'll recognize. I liked the music from this era, I liked he spent a whole year making songs about Tahiary, strained relationship with families and friends.
The Guy That Did It >>>>