First of all for me it is less complex cause I am used to program Java. If I would be a VB/XOJO Programmer I would choose B4x while it is really uncomplex to do. From some reasons it is better to program in Java what you would also do with B4x. While I am using both from time to time I would say: nothing but a few minimalistic things. So it is less complex to program for example Socket Servers with multiple Sockets in B4x and therefore it is less complex to programm Multi threading in Java. It is not so uncomplex. Both, Java and B4x are far away from the simplified programming of Xojo but both are near to getting the Job done with professional tools.
One thing B4x do not have is Linux and MAC IDE. That is for me a real thing cause I am a Linux developer and not using MS Windows. Therefore it is a part of the decision mostly to use Java for programming Jobs.
Using B4x under Linux and on Mac is possible but it starts to be complex to use it on Mac M1 while there are unbeatable problems. Until there is no Solution I can not develop on M1 with B4J.
Another Part is the Cuba platform which uses really state of the art technologies for developming Web Applications. Something I really prefere to use while it helps me to develop faster. But do not forget: Solutions can be done also with B4J Banano. And I was also writing a solution in B4J ABMaterial while it is unbeatable fast und uncomplex for big Web Portals.
Back to the most cases I have to say that I am mostly developing WebApps which are running on Devices with Raspberry PI or another Single Board Computers what makes ist uncomplex for me to develop with Cuba Platform.
Mobile development: is nice in B4A and B4I and also with Gluon. It is for me both with a good usability. But in the Result I was changing to Java and GLUON while it is complex to develop in MAC without support for the IDE. While I changed many of the development computers to MAC there was a way for decisions.
I will also provide the same for B4x later so people can make their own way. But the way I am going mostly (so Java Toolchain) is working natively on Mac and makes no problems at all.
That are my decisions in unsorted cloud to think byself what for you is important. One word to Java: even if you will program with B4J you will have the same Java VM in the background and also the possibility to use Graalvm native image. This should not be your decisionmaker.
Both B4x and IntelliJIdea have no showstoppers. So: try to select what is more comfortable for you instead of humping behind something else.