Which would be better for 3d dev? Should I just go to unity and do 3d dev?
That depends entirely on what your skills, tools, and target platforms are. JME and Unity are two very different engines with very different tools and two very different focuses that fit different developers and studios.
Both are “capable” of 3d dev, JMonkeyEngine is just more “versed”.
You should ask this question on this forum and then provide here a link to your thread.
Kinda like asking which car to buy. Purely personal preference and highly debatable. There are no right or wrong answers. Choose what you want, accept your choice, enjoy yourself
To put it simply, LibGDX is best for 2D, while jMonkey is better for 3D.
You need to do much more work with LibGDX to do a 3D game.