Saw both Black's and Salt Lick. But gotta get to Louis Mueller's out in Taylor. Not just my opinion, but always in a Top 10 and considered a "Heritage BBQ" joint for the US.
In Austin, there is Franklins, but I have never been there (too long of lines - homeless people will stand in line for you for $$).
Yea, I heard that the lines outside of Franklin's is so long that NOBODY goes there anymore