m2ts pass-through is a choice in blu ray ripper.MKV use's a smaller picture frame some people prefer m2ts as it looks better on 60 inch screens and projection screens smaller screens you may not tell the difference.Their are some advantages of MKV as it keeps chapter markers m2ts doesn't and MKV you can use with other helper programs if you like to change the subtitles but some devices don't support MKV so try both out and see what you prefer on your playback device.