Honestly a hard choice. I love the ugly ass style of Wario Land 4, and 1-3 have an interesting style themselves. VB is crazy though, they look so high quality. You can really see Wario's muscles in action.
Me and a friend during a VC did discuss the idea of them doing a Odyssey or Bananza style game for Wario, which I hope is a genuine possibility. Anything to get Wario some platforming+fighting action.
I'll be the troublemaker this site needs. You can call me Troublemaking Care. Or Troublecaring. I don't know. Will post when I set up my trouble factory.