XenForo

vs

bbPress

Create an online community that your customers will love. Vanilla's forum software is used by top brands to engage customers, drive loyalty and reduce support costs. The software is provided free and open-source as a self-hosted solution and can be bought by businesses and enterprises as a managed and hosted solution.

Discourse is an open source internet forum and mailing list software. The application is written with Ember.js and Ruby on Rails, and can be self-hosted in the cloud or on local hardware for free. Discourse also provides managed hosting starting at $100/month, so that you can focus on building a community rather than installing software and managing servers.

Disqus is a Comment-as-a-Service provider that makes it easy to add comments to any web property. It's one of the most popular comment plugins on the market today. With Disqus, publisher can bring their content to life, fuel colorful discussions, efficiently moderate comments, and build engaged communities. The plugin takes only a matter of minutes to setup and is as easy as installing a WordPress plugin or adding a code snippet to your website.

A free and open-source modern forum software written in PHP. With Flarum you can eaisly setup your own discussion froum and host it online.

vBulletin is a powerful commercial forum software written in PHP. The software is built to be easily extended through plguins and customized with themes. vBulletin is used to power many of the largest forum, communities and social site across the web. Over 100,000 sites are currenty powered by vBulletin.