What about GURU (RIP) y'all? His shit was deep and almost too sincere in that one could tell that he was dealing with some issues with his own life. Like you Greg, I coach and this past year I introduced many of my Seattle youngins to GangStarr. They felt it to the fullest. Of course, we did debate as to whether or not Lil Wayne was hot and I lost out. Man those kids love Lil Wayne, but as long as the love is balanced with the REAL from GURU, Mos, Talib, Ishmael Butterfly, GofGab, etc., they'll be alright! I just want them to listen.
And lyricial content is crucial for an MC and most of these guys are poets to the fullest degree. Ya, good production and DJs are essential to the game, but without the lyrics, the poetry, we only have a beat. While you can apply what you will to that beat, e.g. deep throught, your own lyrics, etc., it's the poetry that drove the music that is hip-hop that is the social movement; in it's original form: 2 T-Tables and A Mic! The lyrical content in Edutainment by BDP changed thousands of lives, including mine.
In fact, if I hadn't paid attention the lyrical content in hip-hop, I probably wouldn't have read A People's History of the United States and I know that I wouldn't be the couthful person that I am today. MCs and Hip-Hop alike expanded my mental boundaries, so I could escape my physcial ones; in a small-town, in Kansas, possessed by decades of ignorance, bigotry, racism, hatred, poverty, et. all. So, with respect to that, I say if the MC delivers poetry, if he or she gets deep, or simply stands up for a cause, I'm with them and will always show my respect.
So, maybe the "best" MC doesn't matter in a collective cause. Break Bread.