Out of the ones you listed, I would most likely go for both Pikachu and Zekrom.
But my Top favorite is none other than the yellow mouse Pokemon, Pikachu! He was legitly my first Pokemon in my life! I <3 Pikachu with a passion. In fact, because I love Pikachu so much, I always have to have him on my team, as soon as I can capture one during the game!
Like my buddy TheRealLink, i will most likely choose Blaziken. Hoenn was my favorite region. But out of the i think i will pick Pikachu. he is soooo kewl. but my real favorite pokemon is wailord. WAILORD ALL THE WAY!!!