Best helmet? Probably one that meets
FIA 8860-2018, like a Bell HP77:
https://d3lp4xedbqa8a5.cloudfront.ne...ell-helmet.jpg
Hours of reading about bicycle helmets: https://helmets.org/index.htm
To further winnow helmets, I'd look for one that had a smooth, rounded shape sans 'tail fin' snag points, and one that offered extended rear occipital lobe coverage, and in bright white.
Okay, so you paid big bucks for a helmet that 'bests the tests'. Make sure you wear it in a way that will do you the most good (many folks wear their straps far too loose, and/or the helmet tilted too far back).
https://helmets.org/fit.htm
https://www.nhtsa.gov/sites/nhtsa.do...g-a-helmet.pdf
https://momentummag.com/bike-helmet-fit/