"Tekton is a powerful and flexible open-source framework for creating CI/CD systems, allowing developers to build, test, and deploy across cloud providers and on-premise systems."
Do you know why they are switching, out of curiosity?
The market is definitely very young and I don't think anybody has really nailed down every use case.
There are the parts of the market targeting "business model" use cases like Camunda/Zeebe.
Then there are ETL-style systems like Airflow for dealing with massive data processing.
And still you've got the CI/CD side of things like Argo/Tekton for automating complex build systems/running tests.
Then for systems like Netflix Conductor, Uber Cadence, and AWS Step Functions (among others), you have systems trying to abstract on top of existing complex systems (microservices, etc).
That's not even including low-code spaces like Zapier or IFTTT that try to target making integrations trivial.
It's a crazy world!
At this point in my experience for both (I have much, much more time with Tekton though), Argo is good for CD. It's visualization and syncing of environment charts (we use Helm) is useful.
Tekton is amazing for defining highly complex build/deploy workflows (which we have). Along with Tekton's sibling project Triggers, you can have full end-to-end PR -> Build -> Deploy -> Feedback into Slack/Monitoring/Alerting/etc.
If I had to make a comparison (with my current knowledge level), I'd say Argo is like Angular, batteries loaded with addons you can include if you wish. Tekton is like React, you get pieces and build them into whatever you want.
Argo seems more CD focused right now whereas Tekton really is a “toolbox”/make what you want.