Id still go with +5 armor. Elemental damage is throughout the game more than you think. For example the Charr Warriors in EoTN use Conjure Flame so you know they are gonna deal fire damage with their attacks.
However, defensive wise it sounds like you got yourself covered with a ST prot rit and the DS + LR combo. Once you and your heroes become good enough at this game you will soon realize that you can sacrifice optimization to gear/skill your character the way you want to. Rune your Ranger with w/e you want, equip w/e bow grip you want, etc etc.