Typically rangers will carry an assortment of both melee and ranged weapons. Since they receive the Two-Weapon Fighting line of feats for free, it makes sense for rangers to have a good selection of weapons to dual-wield. Since they get some of the best ranged feats for free, it's good to carry around many arrows as well as a few longbows for different enemies.
One of the best bows for Heroics is the ML 8 Silver Longbow, which can be farmed in the free-to-play quest The Church and the Cult. With a (non-Keen) crit profile of 18-20/x3, many see this bow as good enough to last until late-/end-Heroics.
Rangers are only proficient with Light Armor, so a Mithral Chain Shirt/Breastplate is the best AC choice. Darkleaf armor is a good interim choice if you come across it, since it allows you to wear some Medium Armor types as Light Armor. Many Rangers with high dexterity choose to go with Armored Bracers and Robes instead of armor.