I usually go diving in the Tobermory Area, I just got back from a trip to the long point area that I make several times a year. They both have good wrecks.
I have only been to Brockville three times in which I spent long weekends there diving as much as I could, usually three times a day. The fact that I can wear my warm water wet suit in brockville gets some big points. The several times I have gone the water was warm enough and there was no diff all the way to the bottem. The vis, I could still see the surface from 100 feet, which beets anywhere else I have dove. There seems to be many wrecks to choose from and there is a variety of skill levels to choose from.
I might say that Brockville would be at the top of my list but it is far away for me, I think like five hours or so. I have not dove there as much as I have dove other places so that also might slant my opinion.