I like Blue Mitchell's Riverside sides (always wanted to use that phrase) better than his Blue Notes - heresy, perhaps, around here, but just a personal opinion.
I can recommend Blue's Moods, Out of the Blue, Blue Soul, and The Cup Bearers with no hesitation.
Big Six seems to be pretty highly regarded, but I've yet to be able to get into that one, even though Wilbur Ware plays on it and his presence would normally make it a must for me. I'll have to keep listening to it.