I agree that Redis is "good", I wouldn't put it at the level of HAProxy - particularly when it comes to "what stuff is deliberately kept out of the open source version".

If I had to choose a project/tool to put at a similar 'level' as HAProxy in terms of: doing one thing well; a working open source project with a private company backing it; and a well run project, I'd say it's Varnish, which just happens to pair very well with HAProxy.