Viper ... best choice 30 fhr 13 mdr 35 resist +1 skill, sure coh has 30 more resist and +1 more skill.. but viper is needed for that 105% fcr bp in pvp, 13mdr which is also good in pvp.. and a free socket to put 5/5 facet in for more damage.
CoH is more of a PvM armor, while viper is more of a PvP armor