Due to the age and phrasing of the question, I will assume the asker would like to decide between the two for an in-game playthrough of Black and White. Other possibilities are addressed in less detail.
Vanillite is available earlier and more consistently than Cubchoo, catchable in the Cold Storage at any time compared to Route 7 only in the winter. This makes it more immediately useful, though Vanillish evolves significantly later than Cubchoo (Level 47 vs Level 37, respectively).
In terms of battling, both do fine against what you'd expect, but their low defenses mean they struggle against opponents they're not super effective against. This is one department where Beartic has the edge: it boasts vast movepool diversity via TMs and Superpower via Move Reminder. Vanilluxe, on the other hand, basically only gets Flash Cannon and Uproar as non-Ice moves. Beartic also has higher Attack at the cost of lower Speed; while this is typically a beneficial tradeoff, Vanilluxe may be more useful against opponents like Drayden's/Iris' Fraxure.
In sum, Beartic is generally a stronger choice thanks to its movepool diversity and high Attack. It's set back by its annoying conditions for capture, but if you have the patience, it will be a more useful team member than Vanilluxe.
Beartic
- Icicle Crash (Level 37)
- Superpower (Move Relearner)
- Return (TM purchased in Nimbasa City) / Strength (HM)
- Shadow Claw (TM in Celestial Tower)
In other contexts...
- In playthroughs of B2W2, XY, and SwSh, Beartic is generally better for the same reasons as above, particularly since Vanilluxe either arrives later, is less helpful into boss battles, or evolves too late compared to the game's level curve.
- In competitive, the two typically occupy different tiers or different niches. Vanilluxe is generally more helpful thanks to its Snow Warning Ability, but you should check Smogon's Viability Rankings of whichever tier you're playing instead.
- In the TCG: play a REAL Pokemon game, you nerd.
- In culinary preparation: eating too much Beartic can lead to hypervitaminosis A, particularly if care is not taken around the liver. By comparison, the worst Vanilluxe can do is a stomachache.
