I'm not conceding any of those three. Warner may be senile NOW, but he fought vigorously for the troops on the Armed Services Committee for years. Robb was a useless playboy, but not malevolent to my knowledge (plus his office did get me Clinton impeachment tickets). I barely remember the name Trible.
I think Webb's got a lock on Worst Senator Ever.
Interesting take based on his first three months in the Senate. Warner organized a third-party run against Ollie North who was challenging Robb (who defeated Trible) and said, holding his fingers about a half-inch apart, "I'm about THIS worried about the conservatives." Warner as Chairman of the SASC put ALL USN officer promotions on hold because of Tailhook 91. Robb's record speaks for itself. Trible, a Republican, was widely derided at the time as the Stupidest Senator. Webb may prove himself to be the worst ever, but he's got some stiff competition.