What version?

What version work better with fw3.1.5 in APM2.5 ?
Last version …or another older version.

Thanks in advance.

They all work fine with v3.1.5 (as well as past and future versions), the latest version will have the most improvements, corrections and new features but there is a (very) small chance of something minor not working correctly, usually if this happens then it’s corrected quickly or you can submit an issue for it.