You might have come across this already, but we maintain a collection of article extraction rules for various sites here https://github.com/fivefilters/ftr-site-config - it was adapted from a database maintained by Instapaper in its early days and today has contributions mainly from users and developers of an open source Instapaper/Pocket alternative called Wallabag: https://github.com/wallabag/wallabag
Also usable with a free version of Full-Text RSS available here: https://bitbucket.org/fivefilters/full-text-rss/src/master/