one year canon has the coolest thing out there the next year nikon does.
for the most part as far as glass goes they are pretty comparable, nikon might have the advantage when it comes to their supper high end stuff. Overall you are going to pay a little more for Nikon's high quality stuff though.
For a consumer who just wants to take pictures, just go to a camera store and play around with one of each (40dx or 60d and whatever the rebel series is at now) go with the one that feels the best in your hand, and the controls come naturally to you. Nikon and Canon each have different menu set ups and image control functions.
For the consumer who is a more interested in photography and wants to invest in high quality glass, but does not have a ton of excess cash to spend, again go with which is more comfortable for you to use. But I do think canon has an advantage here because they have a good selection of high quality f4 zoom's and primes that are a little cheaper as well as the fancy expensive 2.8 stuff (17-40 4L, 24-105 4L IS, 70-200 4L (IS option), 200 2.8L 300 4L, 400 5.6L. Where as with nikon if you want to go for high quality glass you have to get the really expensive stuff (canon offers this as well).
For the professional, you should not be reading what I am writing, and be doing your own damn research.
Also one thing you might want to note is that Nikon lens's are black whereas all of canon's higher end long lenses are bright fucking white with a big red ring on the end. This does a really good job of saying hey I'm a photographer (and I may be taking a photo of you, it also does a good job of say I have $10,000 hanging around my neck and possibly another few grand in my bag. There are places where this can be annoying, and it can be convenient to being a little more conspicuous . On the other hand it can make you a little more legit if you care about that.