Well, depends on what purpose. I hear the FN's are sturdier than the CN's (I only have FN's so cannot compare) BUT the CN's are safe for kits w/o babyproofing if I'm not mistaken.
A LOT of people prefer the open spacing on the FN because they can stick their fingers/hands in to give scritches throughout the day w/o having to open up the cage.
I think, if babies aren't in your future...go with the FN. May someone with input on the CN can comment. And as a note, I haven't seen the best reviews about the FN182's...as opposed to their older counterparts the FN142's.