Of those choices, I'd go Theif or Arcane Trickster Rogue, but with the Bard in here I'd rather have a Ranger, Warlock, or Monk. Very versatile classes, that do some things the other classes don't. You've got a strong front line, the Bard is an excellent skill monkey and face, Druid and Bard are good magic users, you're definitely good on crowd control and support casting.
But if it has to be from those choices, Rogue is the guy to be, IMO. As a skirmisher, you can run the back field or be front line in combat, as needed. Out of combat, by focusing on different skills from the Bard, you cover just about everything, and it's fun to play.