I have used both in our organisation and redash is still being used. We implemented Metabase more for point and click ad-hoc queries. Redash doesn’t do that yet as you have to write SQL or any other query.
Metabase for us had a lot of limitations and lacked support from community or developers. Simple things like you can’t change first day of week for charts, it is hardcoded at query level to Sunday. Our org. Same with assuming timezones.
Redash for us has value for our analysts writing queries, and dashboards but also we give our entire org access to write and read all data ( queries and dashboards). For PMs and business users, the dashboards are easy to read and refresh. The number of data sources supported is huge as well.
If you have specific use cases, I’m happy to discuss more.