This.
The first and second time around it's really amazing and seeing Sephiroth walk through those flames so casually with a nasty smirk on his face and then watching Cloud work out who he really is, is really deep and awesome to see.
ninth or eight time round ? We know this already. We know that Cloud is telling fibs in Kalm, we know that Cloud isn't real Cloud. So it's lost it's impact.
Plus it's a huge lie, so it's almost pointless.