LBJ? A bad dude, yes. But I would argue that the sale by the Clintons and their DNC of the Crown Jewels of our missle and nuclear technology to the ChiComs for big money payouts qualifies easily for Most Evil.
Clinton is evil, but I lay many needless deaths of many in Vietnam at his feet (along with McNamara). They sent American boys to their deaths knowingly and without any intention to win. LBJ even lied to Congress to expand that effort.
I consider sending Americans into war the most weighty decision a President must make. LBJ did it as easily as deciding what to have served at a state dinner. For that he gets my 'most evil' nod.