There has been a lot of discussion, as well as disagreement, about this question. In the final analysis I am not sure it matters. I have always been a flat-felled seam advocate. But the stitched down french seam is used by many professional stitchers in place of the flat felled. Personally I think the flat felled is a little easier to construct, but other equally skilled folks find the folded french seam easier.
You picks your poison and takes your chances.