There is no best, only what you like best. MRC is not one of them.
SoundTraxxx recommends the below for the Bachmann 2-6-6-2.
http://www.soundtraxx.com/choose/step3.php?t=ho&s=Bachmann
You can cut back the shrink a little on the Tsunami, pull the 9 pin connector and install the tender 9 pin connector. The below link will show you how to do this in Curriculum and SoundTraxx links.
Store the links in Favorites. I can see you will need them.
I am sure it was not obvious but this discussion should be in the DCC and electrical forum. Some may subscribe only to that forum.
Rich