If you're coming to KC, this my be of some help:
The A-Z list of Kansas City-area barbecue restaurants, food trucks
My opinion of those you listed:
Bryant's: great meat, don't like their sauce. I have taken Gates BBQ sauce into Arthur Bryant's before.
Joe's: A must. I've waited in line 60 minutes before, and I hate waiting in lines. Can't go wrong with a Z-Man or their ribs
Jack Stack: Was alright. A little too formal for me. The atmosphere has more of a steakhouse vibe to it
Gates: Great sauce and great atmosphere (Hi, may I help you). Been many times to most (if not all) of them. Food is usually on, but there are times I've been and it misses.
Q39: Like Jack Stack, the food was good, but didn't care for the atmosphere. It has that 'industrial for millennials' look/feel.