Aint he that cat from oakland? I could be wrong but I know he's from the bay. I aint heard freestyle though, so I can't judge. Anyways, here go my list:
Big L (though he did repeat a lot of his old freestyles)
Old Eminem (it's funny, I haven't heard a freestyle from him for like, 2 years. It seems like he's too busy getting married)
Cassidy (dude is a dope ass storyteller and lyrical as all hell)