When comparing Bugsnag vs BitBucket Issue Tracker, the Slant community recommends Bugsnag for most people. In the question“What are the best self-hosted bug trackers?” Bugsnag is ranked 13th while BitBucket Issue Tracker is ranked 14th. The most important reason people chose Bugsnag is:
Clear, concise documentation. Plus [docs on cross-domain script errors and enabling CORS](https://bugsnag.com/blog/script-error).
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Great documentation
Clear, concise documentation. Plus docs on cross-domain script errors and enabling CORS.
Pro Email, chat, sms notifications
Bugsnag can be set up to send email notifications as soon as exceptions occur. It can also integrate with a number of third-party services that can be used for notifications including Campfire, HipChat, Twilio SMS and custom solutions via Webhook.
Pro Automatic issues/ticket creation
Bugsnag integrates with a wide variety of 3rd party tools to automatically create issues or tickets. Integrations include GitHub, BitBucket, UserVoice, Trello and many, many others.

Pro Has a free plan
After a two-week full-featured free trial period the user is limited to 2,000 errors/month, 1 user and 1 project.
Pro Exceptions are grouped
Bugsnag groups similar exceptions together displaying the number of occurences so that there's no need to deal with each instance of the error separately.
Pro Exceptional documentation organization
Their documentation was well organized, easy to search through for the platform of choice and quick work of full product integration.
Pro Supports Unity 3D
Drop in place integration with Unity 3D, only a simple API Token configuration on game object and everything was up & running with almost zero code written.
Pro Supports phabricator integrations
Not many products have decided to finally start doing this, phabricator now has a champion.

Pro Source map support

Pro Stack traces
Pro Client libraries are open source

Pro Report uncaught errors
Pro Good web UI
Pro Free for up to 5 users
You can use BitBucket for free if you have 5 or less users (or try it out for free). Price brackets are for 10, 25, 50, 100, or unlimited users (it costs $1 per user per month, or $200 for unlimited users).
Pro Native application for both Mac and Windows
Atlassian, the company behind BitBucket is also behind SourceTree, a free application for Windows and Mac wich works as a client for both Git and Mercurial which can be connected to BitBucket and other code hosting services.
Pro Supports both Mercurial and Git
Has full support for both Mercurial and Git VCS.
Cons
Con The tool seems flaky
De-obfuscation doesn't always work on react-native projects.

Con Blocked by ad blockers by default
Bugsnag is blocked by the AdBlock EasyPrivacy filter.
Con Integration with other tools is not as good as github
Most of the 3rd party tools ( bug trackers, CI servers, chat servers, etc) always integrate with GitHub first, and either don't integrate with Bitbucket at all or do sub par job in it. For example there are 3 separate projects to allow building and verifying pull request submissions on Jenkins CI server and there is only one viable one for BitBucket and that one is really buggy and lacking many features.
The only exception to this rule is Atlassian products like Jira.
