I'm affiliated with neither toolkit, but I've tested both, and compared with other offerings such as the Unreal, CryEngine and Unity toolkits. Personally, I find Unreal and CryEngine to still be quite a bit ahead of Godot and Unity, and jmonkeyengine FAR behind everyone else. Others will have other opinions, some of them due to ideological fanaticism for example.
Parts of that is because of how well-designed the ability to interface with other code etc is. Godot and Unity still have some hoops you need to jump through, in my opinion.
Another reason is workflow. CryEngine and Unreal Engine still have a pretty well-designed default workflow, that you can still change if you want. Jmonkeyengine suffers from the usual open-source mentality of "oh, you can build everything up from scratch!", which means "you HAVE to build your workflow from scratch"(Incidentally, this is why many open-source toolkits in other fields outside software development and mathematics etc fail to gain traction: The users don't want to have to invest months of effort, or lots of money, to build up an entire workflow. I know my friends who work in GIS have that complaint for example). You also see the same issue with graphics programs etc. Photoshop vs GIMP for example. Proponents of GIMP often argue that "But, you can modify the program!" etc, while Photoshop has been designed, over the years, to have a workflow based on aggregate collected advice from artists all over the world. Blender(*) had to give in and adapt slightly towards a more Maya-style(*) workflow, instead of the old and utter crap in-house workflow designed by programmers for programmers style used at the design studio where it was first written. In light of above, Godot is a step above the usual open source offerings, in that it has a well-defined default workflow, and I find personally that it edges out Unity in that regard too.
* And that's even when factoring in Autodesk crapping on Maya's workflow. Non-3D artists and 3D artists who were not around for the mid to late 90's and early 2000's don't understand just how much of a revolution Maya was when it came out.