Each has their own set of strong points regarding JIT, AOT, GC capabilities, which one to select is usually based on the use case.
Unless doing something special, you are pretty safe using a regular OpenJDK distribution.
Looks like muddy waters to me. A shame really, they totally ran the JDK release management into the ground.
Commercial JDKs have been a fact of life since around 2000.
In fact, for a very long time, those commercial implementations were the only ones offering production quality AOT compilers and JIT caches for Java.
The JIT caches that now exist as free beer on Hotspot and J9, come from J/Rockit and Websphere Real Time respectively.
Also if you want a GC with real time guarantees for embedded software, PTC and Aicas are pretty much the ones to go to.