I am having both systems as my hobby is to collect gear.
What I like about Nikon
Nikon is generous to bring high-end features to lower-end cameras (sensors, weather-seal, built, user-interface, etc) while Canon like to cripple features in low/mid cameras.
Nikon maintains quality in all/most of its products while Canon restricts quality to high-end products. (but Canon is slowly changing)
Its cameras are photographic tools with instantly accessible functions while most of Canon's feel like menu-driven appliances.
What I like about Canon
Acquires focus faster, good for sports/birding
Image (personal preference)
Fantastic series of USM(=SWM) prime lenses 24f1.4, 35f1.4, 50f1.2, 85f1.2, 135f2, 200f1.8, in addition to the super-teles with IS/VR, which Nikon is just starting to make.
As for service, I think both are good, but I feel Nikon is better. Waiting for Canon service feels like waiting in a hospital. But that's just me.