Solution 9 is awful, I hate the entire area and preferred it during Operation Blood because I'm a sadist and enjoyed the carnage of watching it burn to the ground.
I go in, buy whatever with Tombs or crafting/gathering turn ins and am immediately out of there.

My personal favorite was probably Revenant's Toll, probably for the nostalgia of the place but I won't say that Eulmore and Idyllshire aren't fighting for that 2nd place title.
No real opinion on Radz-at-Han or Rhalgr's Reach. They served their purpose well enough but I didn't feel any sense of attachment to those areas.