Which version of MSXML should I use?

Question

Seems like this would be a common question, though I could not find it on SO.

Which version of MSXML should I use in my applications, and more importantly,

Answer 1

If you need to support Windows OS versions prior to Win2k, then use MSXML3. Otherwise, use MSXML6.

MSXML4 is in maintenance mode.
MSXML5 was never actually supported for use outside of MS-Office.

See:

• List of Microsoft XML Parser (MSXML) versions
• Using the right version of MSXML in Internet Explorer