I cast my vote for the Stryd. After that, I assume they are pretty much all the same. Stryd maps your movement in 3-D space, so its distance accuracy is most likely to be best. The others simply count steps and multiply by a calibrated stride distance.
That’s not at all how the ‘others’ work. Just about everything available as an ant+ or BLE footpod measures acceleration (not movement) in three axes via accelerometers, like the Stryd you mentioned. The hard work is done with the software; figuring out the magnitude and direction of the force(s). The Stryd does have sensors in addition to its accelerometers, which I suppose has the potential to decrease error and reduce the need for calibration…but I don’t know much about Stryds.
Just about anything with a little calibration will be as accurate or more accurate than a treadmill for estimating pace and distance. Personally, I like the heart rate footpod combo straps. Something like a Scosche Rhythm24 works well for me on the treadmill because the bluetooth talks to the treadmill, the footpod info is dialed in and the HR and pace/distance go to my watch for easy recording.