Maybe I'm reading what you said wrong, but I know that you can't get canon glass on a nikon body. However you can get nikon glass on a canon body.
Back to thread topic, it really comes down to preference. So far I've preferred nikon for my needs, and I do like the UI more. But again preference. Some people are brand loyal whores on both sides; don't be that guy. But what I will say is give both a try. Demo bodies, etc. I mean like I said I shoot nikon, but when the 5dmkiii came out I was open and actually really interested. As you invest in glass though, it will be harder to switch brands. If I were to switch right now it would be a pain, and I don't hardly have any glass compared to a lot of people out there.