Since we started developing websites using Joomla!, we have used the Xmap extension as the desired sitemap component for all our sites. As Xmap however now has become obsolete, we had to replace this excellent extension.
We chose to go for OSMap (https://www.alledia.com/extensions/osmap/) which is a continuation of Xmap.
We have now finalised this migration on all our sites and listed all new XML sitemaps with Google and Bing/Yahoo search engines respectively.