Many of the quests here start a chain of quests that lead to a particular set of gear, a weapon, or even a new location. These quest lines are sought after by many. The following links will lead you to the starting quest in the line and will have links to follow-up quests.
Celestine Ward(Armor/Weapon)
Hunters League (Armor/Weapon)
Craigwind Ridge (Weapon)
Coterie Infineum Sanctuary(CIS)
Swamp Armor
Trengal Keep
Feline Veil Mask
Xennumet
Tomb of Lord Tsang
Dargun's Tomb
Ancient Port Warehouse (A.P.W.)
Pantheon of the Ancients (P.O.T.A.)
Black Wyvern Down
Griffon Mount Line
Unicorn Mount Line
Shadowhound Mount Line
Book of Morfare
Journey Boots
Lucent Circle