I certainly enjoyed the sequel more, mainly thanks to the small features like the Repel prompt, the Medal System, new areas, yadda, yadda, yadda. However, the sequel storyline is without question incomplete without first playing the original, so I would certainly recommend both. Start with Black or White, then after you finish that, play the respective sequel. Black -> Black 2 or White -> White2.
Also, do not forget to use the Memory Link right away when starting the sequel!
3DS Friend Code: 4012-4489-0237
My Friend Safari: Ground with Sandshrew (Slot 1), Camerupt (Slot 2), and Diggersby (Slot 3).