As far as I can piece together stuff, it's basically this:
-His #1 choice is Tampa, but they really have no money for him. If they can come close to or match the other offers out there, he'll take that easily.
-The next choice I would have to imagine is Toronto. You have space for him both in the cap and on the team, and certainly has that hometown advantage. However, I do also feel that you have competent management that may hesitate to truly want to pay him the top dollar. You won't go as cheap as Tampa, but I think with where you are in the rebuild, getting Matthews does reduce the need for him, and the fact that he hasn't been as strong as he was before, I get the sense that you guys have sort some of internal cap on what you would pay him.
-After that, then you come in with the wildcards. Buffalo has come out and stated they're willing to back up the truck for him. Wouldn't shock me to see some other un-named teams also potentially offer a boatload of cash to entice him in.
-Then you also have who I would ironically call the "big 3": Detroit, Mtl, and NYR. None of them can really fit him in as it stands, but certainly keep coming back in the rumours and no matter how much there are parts of the negotiation that don't make a lick of sense to them, you can't really count them out.
Now, none of us really know his true motivations, but really, it may actually come down to the sell job the teams take with him, and then how much they're willing to spend. The 10.5M per year number keeps seeming like the "right" number, but you have to think that if someone is willing to offer up to 12M, that really changes the order. Then when you have this whole "sign and trade" stuff coming in as well, that also really throws a wrench into things as it opens up new options.
I do think a lot of it will truly come down to how much are teams willing to pay. If Buffalo truly offers 12M a year, or someone else comes in at that number, then I'm not sure the 10.5 from others would cut it anymore. And I think you have a lot of teams who are trying to figure out how much is it actually worth to pay to him, without completely destroying either the rest of their team or their future potential.