The important thing you need to know, is what ever DSLR you choose, you're married to that brand when buying lenses, flashes etc. - except of the 3rd party products, of course.
Nikon or Canon make a lot of sense, since there's plenty of 2nd hand gear available for these - it seems that my area has a bit more Canon stuff available, but it might be different around your place. Quality-wise, I don't think there's much difference between the two brands, the main reason for discussions seems to be that many people are loyal to their brand.
I use Nikon, of course. Who would want to use a Canon, pfft?