So, you want to know where to go if you need something, somthing being completely undefined.
Well, the answer is, the nearest store that has whatever you want.
Toronto's a big place -- it's silly to travel 30 miles to buy a UV filter.
Henry's is a big chain, with stores in Ancaster (Hamilton) Oakville, Mississauga, downtown Toronto, Scarboro, Pickering, Vaughn, Oshawa, Thornhill and probably some I forgot.
All of these have Lightspheres and flash meters, and low to mid level bodies (D700s, 5D Mk II, probably, and good polarizers in all normal sizes, and a reasonable array of film, and SB900 and 580EX flash guns.
For the big DSLR cameras, go to Henry's downtown. But that does not sound like what you want.
Vistek is the pro store in town -- three storeys in the Queen Street store downtown, and this is worth a visit just for the fun of it. Big printers, lots of pro studio flash, giant tripods, wider range of lenses. This is the palce to buy obscure cables or a studio flash modeling light bulb.
Vistek Mississauga is good for a visit if you're nearby -- Mavis Road south of Highway 401, north of Highway 403
Blacks is a low-end retail chain -- only good for the basics, or frames, except for a couple of stores it aims at more serious photographrs. But there's a Blacks around every corner.
Downtown Camera is a block from Henry's main store, has lots of stuff, including top of the line cameras. But if you are that close, why not walk to Henry's?
Henry's downtown is closed on Sundays, most other stores are open from noon until 5.
BAK