Klinklang has a very high defense, and is a steel type, so he has a sizable number of resistances. It also has a good Special Defense and Speed. However, it has a bad moveset (aside for it's two good signature moves, Gear Grind and Gear Shift). You may have problems utilizing it's decent attack, since it's movepool is largely comprised of only a few physical moves. Klinklang is also weak to Ground, Fighting, and Fire, 3 widely used offensive types. These weaknesses can be somewhat mitigated because Ground and Fighting are normally physical moves, meaning Fire is your true threat.
Vanilluxe can be considered a partial opposite to Klinklang. It has a high special attack and a good movepool. It also has a decent speed. However, with it being Ice-type, it has weaknesses to Fighting, Rock, Fire, AND Steel, three of which are still powerful offensive types. Also, unlike Klinklang, Vanlluxe only resists Ice. Vanilluxe only has a decent defense/special defense, meaning it may not last as long on the battlefield. Unless you can eliminate the enemy fast, it may faint fast.
Depending on your needs, you may choose either Klinklang for a reliable tank, or Vanilluxe for a reliable sweeper.
Hope this helps!