1. The Vale a variety of mobs and terrian and its just fun and you can get a lot of xp on your first run through it.
2. tangleroot its just fun
3. Amarath another fun one
4. The desert big area lots of different things to see and kill
5. Kings forest fun and you might get to kill a dragon
6. High road another fun
I just like the slayer areas in general if I just have a few minutes to goof off I can jump in the one suited to my level and have a little fun.