I think either Wario Land: Shake it or Wario Land 4. Shake it was my first Wario game and i loved it. The art style, music and gameplay were all excellent! Wario Land 4 was also a lot of fun. The graphics and gameplay were all great as well. Overall, both amazing games in my books!
My friend said he is planning on buying one cuz he doesn't have a switch, So yea its perfect for people who don't have a regular switch and its $100 cheaper!