There's no rating system (that I know of) employed by makers of ski/snowboard helmets here in the USA. You could check to see if any of the models carry any ECE (European Union) ratings, but other than that, there is no single standard by which to compare them.
I just picked up a Smith Holt yesterday. Safety, they all use the same type of foam insulation. Difference in price seems to be manufacturer, padding (comfort), room for adjustments, fixed vs adjustable vents. Speaker system ready, speaker system already installed and detail to design.