Hi we have used Redmine long time. There is light version og Agile plugin from RedmineUp which makes Kanban very usable. :
More great features comes from:
- Pivot Table plugin : https://github.com/deecay/redmine_pivot_table
- Issue Evm plugin : https://github.com/momibun926/redmine_issue_evm
- Checklists plugin (Light version) : https://www.redmineup.com/pages/plugins/checklists
- WBS plugin : www.easyredmine.com
- MindMup plugin : www.easyredmine.com
- CRM plugin (Light version) : https://www.redmineup.com/pages/plugins/crm
- CMS plugin : https://redmineup.com/pages/plugins/cms
These will change standard Redmine installation to multitalented project manager. Usability is excellent and in real work the most modern UI does not mean anything better. You can get themes to make Redmine look better.
We also use Taiga but is is very prone to issues and glitches. It looks cool and modern but user experience is that Redmine is more reliable and flexible. Using it in marketing related projects.
OpenProject is limited without subscription and you get more open source operability and features in Redmine. EasyRedmine is Redmine as SAAS and the cost will get ugly very fast.
In Open Source the key is hosting your solutions to keep your data your own and private.