on the input file x.xml I posted your solutions produce the same output.

As Ken asked for more inputs I tried adding a comment and then
the output of your solutions and the recursive solution differ:

$ cat d.xml
<a><b>c<c/></b><b><c/><!--test--></b></a>
$
$ xsltproc d1.xsl d.xml
<?xml version="1.0" encoding="UTF-8"?>
<a><b>c</b></a>
$
$ xsltproc d2.xsl d.xml
<?xml version="1.0" encoding="UTF-8"?>
<a><b>c</b></a>
$
$ xsltproc y.xsl d.xml
<?xml version="1.0"?>
<a><b>c</b><b><!--test--></b></a>
$

I have to ask the originator of the problem for the exact requirements.

<xsl:template match="*[not(.//text() | .//comment() |
                           .//processing-instruction())]"/>

<xsl:template match="@*|node()"><!--identity for all other nodes-->
  <xsl:copy>
    <xsl:apply-templates select="@*|node()"/>
  </xsl:copy>
</xsl:template>

</xsl:stylesheet>
~/t/ftemp $

--
Contact us for world-wide XML consulting & instructor-led training
Crane Softwrights Ltd.          http://www.CraneSoftwrights.com/s/
G. Ken Holman                 mailto:gkholman@xxxxxxxxxxxxxxxxxxxx
Legal business disclaimers:  http://www.CraneSoftwrights.com/legal