I settled on AddToAny, and I have to say it worked perfectly right from the start. It offers links to a wide variety of services, including Facebook, Twitter, Digg, Reddit and StumpleUpon, to name a few. AddToAny adds the sharing tool at the end of all individual blog entries and articles if you specify the "blog" and "article" category types.
Installing add-ons in Drupal is very easy, and this module in particular only needed one click to be activated. Configuring AddToAny was also simple, once I found the settings in the Configuration menu of the Drupal control panel.
Social Bookmarking Genius, I was told in repeated reviews, was the best free social media add-on for Joomla, so I dutifully went out to get it.
I installed the component, activated it, and... nothing.
Once again, the Module Manager settings for the module required that I set a position, and it was not clear what that position would be, since the articles I wanted to have social linking were located all over the site in various locations on the pages. This was a universal problem with any module I tried; it would require a position setting, but no position I attempted would work. Nor could I skip this setting.
In the end, I was not able to determine a solution for this problem.
One area where Joomla did excel here: The capability to turn on SEO-friendly URLs is a highly visible option, which should make Joomla websites easier for search engines to index.
Given my success with the AddToAny module in Drupal, I was pleased to note that AddToAny had a popular module for WordPress. But after installing it, I found that it works differently in WordPress -- it added the sharing tool to all pages in the site, based on where I placed the AddToAny widget in the template.
However, the WordPress version does not include Twitter or other social tools, just RSS feed information. To compensate, I located the Tweet This plug-in, which uses the Oauth API to plug straight into Twitter. Tweet This was instantly ready to go and attached to articles as needed.