Nikon or Canon for dslr?

Should I get a Nikon D5100 or a Canon T3i for my first dslr. I'm probably going to stick with the company chosen for years.

I don't know why, but my friend who specializes in camera's and equipment always laughs and mocks the Nikon camera's… Plus he has a canon, so I would say go with that

What it basically comes down to is which one feels better in YOUR hands. If you like the canon feel, get canon. If you like the Nikon feel, get Nikon

Both cameras and brands are excellent so you can't go wrong with either. Try out both of them at a nearby camera/electronic store and see which brand's user interface is more comfortable for you to use.

Either or. Nikon & Canon cover 80% of the market.

They are both so similar it shouldn't be that much of a hard decision. Both have lots of MP, articulating screen, good video and great sensor. There isn't something that would make the other one so much better.
Here's a DSLR Buying Guide - http://www.the-dslr-photographer.com/2009/11/which-dslr-to-buy/
Here's a T3i Review - http://www.the-dslr-photographer.com/2011/05/canon-eos-600d-rebel-t3i-dslr-review/

While the Canon Rebel T3i / EOS 600D offers a number of impressive advanced features, the camera's core technologies do not match the capabilities provided by the Nikon D5100 with respect to sensor performance, metering, autofocus, and image processing ability. Since these factors are key determinants of image quality, the Nikon D5100 provides an edge, and delivers a greater consistency of enhanced image quality versus the Canon Rebel T3i as seen in our side by side comparison tests.