I was thinking about these mixtapes since I answered. I would say Bootleg MFer Vol 1 is necessary. It's a lot of great guests & freestyles. Some of his best studio tracks, too. I think I heard 1 or 2 tracks on Rise's R.Kive compilation, but everything else is exclusive I think.
Paz, Eso, Majik Most, Celph, Rise, C Rayz, Punch & Wordz....A ton of great rhymes on this double, and really only 5-6 total flops track-wise.