I'll help you out by doing some of the ones people haven't done yet for you...
Brampton/North Bay
Graduating OA's: Francis Menard, Cameron Wind, Brendan Childerley
Graduating other players: Matej Machovsky (signed in Europe), Patrik Machac (signed in Europe)
Potential OA's: Nicholas Foglia, Barclay Goodrow, Matt Macleod, Zach Bell
If Goodrow gets drafted this year and plays in the AHL/ECHL, it makes the OA decision easy in North Bay. If not, it could get complicated. Best guess would be Foglia is the odd man out. Bell and Goodrow would go nowhere, while Macleod fits very well into Butler's system and has improved a lot under him.
Oshawa Generals
Graduating OA's - Scott Sabourin, Matt Petgrave, Geoffrey Schemitsch
Graduating others - Tyler Biggs (highly doubt he returns as an overager), Boone Jenner, Lucas Lessio, Scott Laughton (got a cup of tea in Philly this year, could stick), Simon Karlsson (signed in Europe)
Potential OA's - Brian Hughes, Johnny Mcguire, Trevor Morbeck, Colin Suellentrop
Suellentrop would be the only sure thing as an OA (doesn't look like he's signing in Philly). My guess would be Mcguire gets another OA spot as a scrapper type, while Hughes and Morbeck battle it out for the 3rd.
Ottawa 67's
Graduating OA's - Michal Cajcovsky
Graduating others - n/a
Potential OA's - Ryan Van Stralen, Clint Windsor
The 67's will have an OA spot open. Both of those guys will likely be brought back.
Owen Sound Attack
Graduating OA's - Daniel Zweep, Keevin Cutting, Nathan Chiarlitti
Graduating others - Jordan Binnington, Daniel Catenacci, Cody Ceci, Cameron Brace (possibly, if he's drafted and then signed), Gilbert Gabor (doubt he returns as an import)
Potential OA's - Cameron Brace, Steven Janes, Kyle Hope, Kurtis Gabriel, Brayden Rose
The OA situation in Owen sound is VERY murky. All 5 of those players are contributing members. If Brace returns, he's a lock to be one of the OA's, with the other 4 players fighting it out. My guess would be that Rose stays because the Attack defense is losing a lot next year in Ceci, Chiarlitti and Cutting. They'll need a veteran back there. Hope and Gabriel play similar roles so there would only be a need for one of them.
Sarnia Sting
Graduating OA's - Charles Sarault, JP Anderson
Graduating others - Reid Boucher, Connor Murphy (perhaps, although with his injury issues, maybe they send him back to junior for another year)
Potential OA's - Nickolas Latta, Craig Duininck, Alex Basso, Knick Dawe, Taki Pantziris, MAYBE Connor Murphy
Dawe is an easy cut, even if the Sting need goaltending. Pantziris just joined the team from NCAA, but I don't see him being better than any of the other OA's they've got. Unfortunately it's a business, but I can't see him sticking around unless other players are dealt to help the rebuild. Latta no longer counts as an import, so he'll stay and provide leadership at the forward position. Duininck and Basso are also staying. The real tricky part would be if Murphy gets sent back. If that's the case, my guess would be Duininck being dealt.
Windsor Spitfires
Graduating OA's - Alex Aleardi, Emerson Clark
Graduating others - Alex Khokhlachev, Jaroslav Pavelka (can't see Windsor keeping him as an import and OA, probably signs in Europe)
Potential OA's - Jaroslav Pavelka (see above), Remy Giftopoulos
I know the Spits don't have many returning imports, but I still can't see Pavelka back. My guess is the Spits go out and take two high profile imports to rectify last year's disaster at the import draft. That means no more Pavelka. And I'm sure Rychel and management would love to bring in a couple of better OA's who could be available (perhaps one of Owen Sound's).