I found the Chaosium fiction books I've read so far to be entertaining enough.
But, I think the overall most rewarding "Cthulhu fiction" I've read, aside from Lovecraft's original fiction, has been in the form of collections of (generally older) fiction that Lovecraft admired or was at least partly inspired by - such as Dunsany (I would still love to see a nice Dunsany collection that includes the original Simes illustrations!), Poe, Blackwood, Machen, Hodgson, E.R. Burroughs, Robert E. Howard, Clark Ashton Smith, etc.
I wouldn't mind seeing Chaosium produce a series of books collecting the "Weirdest" of this fiction, perhaps with commentary from Lovecraft (from his letters and essays) and other writers, presenting the collections from a "Lovecraftian" perspective.
With a lot of that older fiction having fallen into the public domain, collecting it together in a nice, matching set with useful commentary from any of the vast number of Lovecraft experts/scholars willing to give their opinions would surely be a "low hanging fruit" sort of thing for a small publisher, especially one invested as heavily into the Lovecraft fandom as Chaosium is! (At least, from my armchair, it seems like a comparatively easy and low-risk "win"....)
With that in mind, I thought Chaosium's The Terror and Other Stories (Machen), The White People and Other Stories (Machen), The Three Imposters and Other Stories (Machen), and The Yellow Sign and Other Stories (RW Chambers, a sort of "Best of" The King in Yellow, which in turn seems to be a sort of "Best of" Chambers) were quite excellent, and I'd recommend them all in a heartbeat to those who enjoy Lovecraft's fiction.