Definitely not Willowgrove. That place isn't good at all. M'aiq lied to me.
If you travel the rivers in Malabal Tor and kill all the Hoarvers you can rack up a lot of XP, as well as a lot of water plants and pure water. And the various Orc settlements throughout AD just feel more satisfying to wipe out after the headache they give you in Velyn Harbor.
Dro'krin Monastery in western Reapers March is a good grind spot. Lots of quick respawning mobs. But they do have a lot of fire attacks. But it's where I grinded out my last 2 veteran levels.