I cannot speak about Talend since I have never used it. I think it depends on what you want to do and into which environment you will have to integrate and what tasks you have and what kind of people and talents you have access to.
My experience with KNIME is in these stages
- standalone on a Mac/Windows machine (limited to what power this machine brings) - you might connect it to a wide range of databases and sources
- KNIME Server ($) gives you power of automation and team collaboration
- KNIME connection to Cloudera Big Data cluster where KNIME is you GUI/cockpit and automation engine
The philosophy of KNIME I think is well captured in the first article below. Give all analytics people in a company an affordable, easy to use graphic software for all kinds of tasks, a tool that would happily connect to all sorts of data sources and can run code from R and Python on top.
Sometimes hardcore coders do not like KNIME that much because they say: I can do that in xy lines in Python. Yes they can, but KNIME would also do that and one great benefit from my perspective is it sort of automatically does its own documentation thru the nodes and workflows. If you put in just a little more effort you can create a documentation on top.
So if you want to empower a broad range of people to use all kinds of analytics and automate some tasks easier than with VBA or some programming framework then KNIME is your thing especially if you can create a community around it that share code and examples (like on this forum but you might also encourage that within your company).
Considering ETL I see these possibilities in KNIME
- use the integrated KNIME nodes for data manipulation (everything will be done within KNIME)
- use the Database connections with generic nodes that require little or no knowledge of SQL
- use KNIME as a GUI/front end for your own SQL jobs and send them from an workflow to your data base/big data environment that does the heavy lifting
Here you can see a small example how such an ETL job might work (discussion about SQLite that shows the potential of SQL-connections from KNIME)
Empower Your Own Experts! Continental Wins the Digital Leader Award
Gartner 2018 Magic Quadrant for Data Science and Machine Learning Platforms
https://www.kdnuggets.com/2018/02/gartner-2018-mq-data-science-machine-learning-changes.html
Great Power, Great Responsibility: The 2018 Big Data & AI Landscape