Most people these days have a very simple answer to the question of where to hunt: Task Dungeons! Task dungeons are predictable, mindless, unchallenging - the very definition of a grind. Those things also make them fairly steady experience, and then they provide a nice bonus when completed.

However, regardless of how easy the experience is, three things make task dungeons not worth it, in my opinion:

1. The monsters inside are neither vulnerable nor resistant to any types of damage. This not only takes away the benefit Flex Reavers have in being able to use either Slashing or Crushing damage, it means that they aren't vulnerable to your Spirit-based spells.
2. The camp bonus is a static 50% unless you bring someone along with you. However, bringing more people reduces the benefit of the 'grindy' factors of the TDs. You can get up to 100% camp bonus in outdoor zones and 120% in dungeons, which in my opinion makes up for the loss of task completion bonus.
3. They're boring. Very, very boring. Spending time in these will greatly reduce your fun, regardless of how much experience you're getting out of it.

Task dungeons are always a good place to fall back on if you don't want to travel far, or want a grind, or can't find anywhere else good to go... but I think there are better places.