Hi,
I too live and dive in Ontario most of the time and go often to the carribean for vacation. 4 years ago I was sort of where you are now; what to buy, is it versatile, reliable etc. Something I considered too was servicing; cost of and availablility both at my LDS and possible parts at my intended (initial) destinations. I don't know about anyone else but I prefer to deal locally and in person when it comes to servicing or repairing my gear; having good odds when away that a glitch can be fixed isn't a bad thing either.
Water temps in Ontario range from 35 degrees F (Tobermory) or even less ice diving to the mid 70's in summer in shallower lakes/rivers. Tropics are often 80+. This reality means that there is no single exposure solution for you. You have to make your best guess at what kind of diving are you going to be doing most and kit yourself for that to start.
When I started I bought a good, durable jacket-style BCD with plently of lift for the Sherman Tank weighting system (ha!) and both a 7mm 2-piece and a 3/2 full. As mentioned, cold water regs are a must. At the time I thought I would dive up here about a couple times a month in the spring to fall, after that the yearly trip south. As it turned out however, I now dive WAY more than that up here and have nearly re-mortgaged the house buying better and more advanced gear. Don't get me wrong, the original gear served me well as I grew into the sport and gave me over 200 dives without letting me down once. Still use it occaisionally now and makes great back-up.
If you can look into your crystal ball better than I did and determine what route you will end up going (and there are several) you can get your basics for that and work from there.
In my case, if I knew I would get this enthusiastic about diving up here I would have definately gone BP/W, drysuit and 3/2 full. Covers pretty much everything and the BP/W still travels fine with a 5 lb plate. And it's the most comfortable set-up for that Sherman Tank you need to strap to yourself to sink up here...