My favourite from my collection would be:
Japanese would have to be either TRU exclusive Black Lio Convoy or TRU Exclusive Black Big convoy
US Exclusive would be either Wal-Mart Constructicon Maximus (Energon Constructicon repaint) or Target Exclusive Universe Nemesis Prime (Big Convoy repaint)
I think it's obvious that I love Beast Optimus.
But Exclusives able to get in Canada, I'd have to say Target(Zellers) Purplewave and Sunstorm. (Though like the other I got from Import
).