What about HQ choices? I tend to go with a Librarian and stick him in a tacsquad because I lack dedicated assault(in matches 1250-1500). I think assault marines are quite poor(fire magnets and really vulnerable if you derpstrike), and assault termies are very expensive to get, needing a complemantary landraider with them. But usually it feels like a chaplain is a better choice to go with termies.
Master of the Forge seems only viable with a conversion beamer. How viable? He can be sniped easily. Attach him to a combat squad with a lascannon or similar?
Chapter Master seems absolutely rubbish for his cost, and seeing what the Grey Knights chapter master can do, I have no wish to embarrass myself with them.
Captains seems ok, but like I said it would seem in most cases a librarian or chaplain is more useful.