Hi,
I don't know about the kw11 and kw15, but the difference between the kw19 and the kw17 is the speed rating. The kw17 is a high-performance winter tire (H-rated), whereas the kw19 is only T-rated. Looking at the speed rating of the stock tires on your car might guide your choice. If the stock are H-rated, then you'll probably need to go with the kw17. If they are T-rated, then the kw19 are a better choice.
I think with 205/65/15, you might not get that much of a choice.
I think the kw11 and the kw15 have been more or less discontinued and have been replaced by the kw17 and the kw19.
My 2c.