Ignoring people who have said they don't return and people bb won't bring back, I think this would be an amazing season to watch.
Males:
Will (Bb2, Bb7)
Boogie (Bb2, Winner of BB7)
Dick (Winner of Bb8, bb13)
Dan (Winner of bb10, bb14)
Jeff (Bb11, bb13)
Derrick (Winner of bb16)
Paul (bb18, bb19)
Tyler (bb20)
Females:
Danielle R (bb3, bb7)
Janelle (bb6, bb7, bb14)
Daniele D. (Bb8, bb13)
Jordan (Winner of bb11, bb13)
Britney (bb12, bb14
Rachel (bb12, Winner of bb13)
Nicole (bb16, Winner of bb18)
Vanessa (bb17)