Recommended based on popularity at the time of writing.
Level 1-8: Whichever zone you're doing your Rank 1 hunting log in.
Level 9-20: Western La Noscea between Swiftperch and Aleport.
Level 18-30: South Shroud, close to Quarrymill.
Level 28-34: Eastern La Noscea, Bloodshore.
Level 33-42: Coerthas Central Highlands.
Level 40-50: Northern Thanalan.