We like 17 for one unmentionable reason.

When the carts come down the aisle, we get up and run back to the washroom. We're back by the time they reach 17.

If you are in 6, once service starts you are trapped there until service finishes. (Having flown a lot in F I won't use the F lav when I'm in Y).

You might not be a 71 year old woman like me, so YMMV. But it's a really compelling reason for us.