Great call on Sergei. I would definitely be down for Barnett/Sergei. They also need to get Aleks off his lazy ass and into Dream for a rematch with Josh or for a fight with Big Timmeh
Honestly if you take all the people you mentioned out of the equation the fight I would most like to see is a rematch with Jeff Monson. There first fight was fairly close (I'd give Monson the first and Barnett the second and third.). There is Sergei Kharintov in Dream though which could be a decent fight.