The original Mobius is one of the best most completly developed action/dash cams made. It's only real shortcoming is the older hardware which has been surpassed in low-light, and the bitrate. Can use supercaps for dashcam work. Still a very good cam.
The M2 is no longer made, it has been essentially abandoned by Mobius and never got developed. Not worth a second thought.
The Mini is an action cam, not a dashcam, as it cannot tolerate high heats from summers without some active airflow. It was meant mainly for RC aircraft use and does that type of job well.
The Maxi is meant as a follow-on to the original cam. It's still hasn't been fully developed and while they are occasionally releasing firmware updates to that end, those are slow in coming and the cam still has some bugs which haven't yet been addressed. It has the potential to exceed the original Mobius on all counts, but it is not even close to that point yet, and some of us are concerned that it might be abandoned like the M2 was. Can use supercaps for dashcam work. Due to the slow and erratic development I won't recommend it, but if you can tolerate it's issues it is an OK cam overall as it is now.
I'm not sure your purpose or the setting you intend to use a cam in, but you might do better with a purpose-built "Trail Cam" or one of the other dashcams which may have a better motion detect system. You might also consider something like the "Wyze" cam which is built more toward this purpose. Also you might want to consider recording in low-bitrate as an alternative to motion detect, as that is a more certain approach compared to motion detect which may not activate or be delayed in recording thus missing your target.
Phil