xml, html or xhtml in : Which is the better choice?

Question

For historic reasons we have a mixture of

and

Answer 1

As far as I know, there is no method:xhtml to the xsl:output directive in xslt 1.0.

wc3schools agree with this.

As XHTML is an XML dialect, that's what I would use.

If, however you are using xslt 2.0, might as well use xhtml, since that's what you are outputting.