WOW!
Not only is that question (What's the best BBQ you've ever had?) difficult to answer, I personally think that it is IMPOSSIBLE to answer honestly.
Considering the fact that there are people all over the WORLD who read this website, there are millions of "opinions" of what "best BBQ" should taste like.
The answer, whatever it may be, is totally subjective, perhaps, as it should be.
Personally, I think that the BBQ that I cook on my own grill, in my own oven, or in my own smoker, is the BEST BBQ on the planet.
BUT . .. YOU (personally) may think that it sucks big time.
Even though BOTH of us could qualify "GOOD" BBQ from crap (like a recent posting about "Famous Dave's), when we use the term "BEST", then we have a totally new ballgame!
There are so MANY good BBQ places in the South and Southwest, it could take one a lifetime to test and select the "BEST" BBQ I've (or you've) ever had.
Oh well, your question, although an interesting one, is STILL a sticky one.
Bill