Okay, I'm gonna compare the two Pokemon in their final forms, Beartic and Vanilluxe.
Gosh, these two Pokemon are so similar it hurts my eyes. They are both Ice-types, they excel in an Attack stat, and both of their abilities activate when a hailstorm occurs.
I want to suggest Beartic because it evolves into it's final form earlier then Vanilluxe does, and Vanillish does not have many good stats compared to Beartic. But yet again, Beartic does not have many good phsyical Ice-attacks.
Whilst, Vanilluxe has access to plenty of special Ice attacks (for it's Special Attack advantage), but none of them are very good except for Blizzard and Sheer Cold.
Another good plus, Vanilluxe learns Sheer Cold. xD
But Beartic learns some great coverage moves to hurt all the meanies out there that want to kill it. Therefore, I'll have to suggest Cubchoo.
OMIGOSH SO CUTE :')
However, I do want to note that an Ice-type isn't really that necessary. Especially if you already have a Water-type on the team, I wouldn't even add an Ice-type. Just a Water-type. If you have Black 2 or White 2, and you're willing to trade, get an Eevee from Black 2 and White 2 and trade it over, and evolve it into a Vaporeon. Vaporeon learns many good Water- and Ice-type moves.
Hope I helped. :)
Source: Serebii's pages