Which keyboard is better for levels 2-6 on keyboard?

I have a casio wk-200 I was wondering is this for a beginner? I've seen the Roland and Yamaha on youtube and the stores and I think they sound better then the Casio's. I was wondering which one should I have when I get past level 6 of piano? Right now I'm learning on the casio one. Merry Christmas!! :)