I had to check which forum this was in. My answer would be different in a grilling forum.
I am kind of schizoid?
Been using Kingsford Blue for maybe as long as younger members have been alive?
I still use KB for grilling. I use it for one hour to heat my offset and get the grates clean and "sterile". Just because KB is cheaper then lump.
For smoking, I switch to Royal Oak Lump when the meat goes on, because I like the flavor better.
Note that I use an offset. If I was using an upright? I still might be on KB for the obvious reasons.
Anecdotally and only anecdotally? They both smell bad and kick out a lot of bad stuff when firing up? But I really think the noxious stuff out of KB makes my eyes water and my head spin more. But that is when firing up. I never add anything to my offset or my grill unless it is fully fired up. The lump does seem to burn cleanly and leave little ash?
My only complaints with RO Lump are minimal. It does kick out a lot of sparks? OK, so what, we are making fire here? It burns hot and will not burn as long as KB. Also, the lump is more expensive.
So going back? I never use either until totally fired up. I am very happy with KB for warming a smoker and for grilling. I prefer lump for the extended smoking process, probably because I am not an upright user. I "think" I get better flavor and less ash from the lump. Never press me for scientific details on that one?
The issue will never be settled. Just my thoughts.
Good luck and good smoking.