Q. Is it better to get the current version of 390 Duke or to get the BS6 version or to wait for the next generation which was spied testing? Please let me know soon?

Getting the BS6 version will be my choice because the current version of Duke 390 is absolutely perfect in the segment, be it the looks or the performance. KTM might do some visual changes and refine the a little bit more but that would result in increase in weight and decrease in raw performance as we saw in the 2017 update ( but both made the bike a more appealing package ). Based on these facts, decide whether to go BS6 or Next Generation Duke 390.

If you want a bike now than you can go for it its the best in segment and at the year end you might get better deals on it and waiting for BS6 version doesn't make much sense because the engine is already performing very good so you can go for the current version.