If you want a helmet that is very protective has removeable facemask options, is plastic, and ugly as all get out, and worn by old men, go for the cascade. (No need to flame me for these comments here readers, its just my opinion on these helmets.... it doesn't make it so. One man's mud is another's gold, or something like that).
There are lots of good looking helmets out there in kevlar that get the job done. Granted, protection is the most important feature in a helmet, but its quite possible to find a cool look you like as well.
My top reccomendation would be FNA headgear out of BC. They make 2 full face carbon/kevlar helmets that have total coverage, as well as a handfull of sweet non-facemask car/kev helmets. The one thing on the full-faces' is that the facemask is not removable. Its carb/kev and is part of the helmet (one pice) but its probably about the most protective kayak specific helmet on the market (if you believe facemasks are the way to go.)
For more info and pictures email FNA's owner/builder Faron. He make's em custom for ya, and will email you pics and info. They are relatively affordable as well and extremely durable and quality.