The summary page (1st page) looks very identical. Which one is the one to pick? I am also open to other accel+gyro modules recommendations that is currently popular
what are the primary differences? all 4 of them can do what i need. Its just if im buying one, i might as well get the best one, more leeway to what other project i can use it to.
Buy the one with the X to get the machine learning core.
It is a really, really good idea to learn to read and compare data sheets, before shopping for parts.
We don't know what would be "best" for you.
Hint: to learn about the advanced features of these sensors, check the documentation center at st.com. For example, the machine learning core of the LSM6DSOX is described in this document. That is unlikely to be useful for an experimenter, because everything it does can be implemented in your own code.