First, I started with Netbeans. Then I switched to Eclipse, because everyone I knew used Eclipse and we used an Eclipse-based IDE also at work.
Now, when I have been happy with Eclipse, I was forced by our work team to switch to IntellijIDEA. Until now I don't like this IDE very much, because for me it's complicated, but maybe I will later understand why it was preferred by our team. Maybe it's fully loaded with various tools that I have not used until now and maybe later I will appreciate this IDE.
IMHO, to compare Netbeans, Eclipse and IntellijIDEA:
Netbeans is simpler then Eclipse, Eclipse is simpler then IntellijIDEA.
Netbeans is a lightweight IDE.
IntellijIDEA is most heavyweight IDE I have ever seen. The launch of version 14 will take on my computer (with i7 processor and 16 GB RAM) about 5 minutes or maybe more.
My preferred IDE is Eclipse.
IMO both - Netbeans and Eclipse - are very good IDEs and it doesn't matter which are you using for learning Java.
Install them both and compare.