When comparing Blossom vs Taiga, the Slant community recommends Taiga for most people. In the question“What is the best task management software for small teams?” Taiga is ranked 8th while Blossom is ranked 17th. The most important reason people chose Taiga is:
User stories can be organized in both Kanban and Scrum task management systems.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Slack integration
An update is posted to the Slack channel every time a task is created, completed, moved, or commented upon.

Pro Simple & clean interface
Design focuses on clarity.
Pro Supports both Kanban and Scrum modes
User stories can be organized in both Kanban and Scrum task management systems.
Pro Free and open source
Taiga is licensed under GPL with source code available on GitHub.
Pro Simple to use
Pro Comprehensive Agile software development toolset
Taiga tries offering a complete Agile software development toolset. It includes complete solutions for issue tracking, videoconferencing, documentation (in the form of a wiki) and either a backlog or a Kanban board for managing user stories.
Pro Built-in issue tracking
Taiga has built-in issue tracking tools. The issues can be organized by user-defined type, severity, priority, creation date, assignee, creator, tags as well as filtered by subject. Taiga can also integrate with GitHub, GitLab and BitBucket.
Pro Built-in wiki
Each project has a wiki. It has Markdown support as well as a WYSIWYG editor.
Pro Built-in video conferencing tools
Integrates with either AppearIn or Talky to provide a video conferencing solution.
Pro Migration from RedMine
Pro Export/Import feature
You can extract all your data from one Taiga instance and move it to another one. You can read more here.
Cons
Con No free plan
There is no free plan like for personal use and the minimal cost of $19/month might be prohibitive.
Con Slack integration is really basic
There is no way to interact with tasks in any way - new tasks can't be added, completed tasks can't be removed, tasks can't be assigned, etc. The integration only sends updates to the Slack channel. There is also no way to fine-tune what updates get posted to Slack.
Con No Kanban metrics
Taiga is said to support Kanban but it does not generate any of the usual Kanban metrics (cycle time, lead time) or graph (Cumulated Flow Diagram).
Con Can be overwhelming at first
Taiga presents users with a lot of information and functionality right from the beginning with little guidance. Figuring how stuff works might take a bit.
Con Too much functionality for small projects
While it's possible to disable any unwanted features (modules), the amount of functionality that's present might be more than a small, short-term project needs.
