Assuming you're on a train which crashes, are there statistics about which is a safer seat: facing forwards, or facing backwards?
I think what you're are looking for is an analysis similar to the one published by Vocativ, so if one looks at the analysis and one of the underlying studies published by Robert Thomas Anderson at University of Illinois Urbana-Champaign the safest cars would be 1-2 from the back with seats in the aisle in the front of those cars facing to the rear where 2 rows of seats face each other.
One caveat to that is of course the car you're riding has the same layout and you can actually take riding backwards (some people I know can't).
The safer seat direction and position within the car will depend entirely on what kind of accident happens. If your train derails and hits a bridge, you want to be in the back, facing rearwards. If it is stopped and gets rammed from behind, you want to be in the front facing forwards. If it catches on fire in a tunnel, you want to be at whichever end is lower, preferably facing the door.
Like "where to sit in an airplane", the best place requires advance knowledge of what kind of accident is going to happen. If you know this in advance, the safest seat would be your couch at home.