Reflecting back on both Zoroark and Victini, I think we're going to see Zoroark as the playable Black/White representative.



It was the first fifth generation Pokémon to be revealed, it starred in a movie, it's heavily promoted, it has a major role in PokéPark 2, and it's featured in Pokémon Conquest.



Victini also has a lot of that going for it, but at the end of the day, it's still a cutesy flying legendary in the vein of Mew and Celebi. I can very well see Victini being one of the first Poké Ball summons revealed on the new Dojo.



With that said, Genesect's role and impact remain to be seen. Deoxys was a popular Ruby/Sapphire Pokémon in a similar position, but there's no indication that it was ever considered to be playable, so I'm not sure how well Genesect might hold up. We're two years into the fifth generation and it still hasn't been seen, whereas Zoroark has had all of that time for exposure.