what colors is your favorite? 可以这样说吗?

what colors are your favorite?
what color is your favorite?

不行，这句话有一个语法错误，colors是复数，和is 主谓不一致
你应该说：
What color is your favorite?
or
What is your favorite color?

我只听说过

What's your favorite color?

Which color is your favorite?

可以，但前面color不要用复数

what is your favorate color

what is your favorite color?