I prefer Nikons. My family and I have had 6 Canon point and shoots, so when hunting for DSLRs, I was 99.9% convinced that I was going to get whatever entry level Canon DSLR was on the market. I went to the store, picked up a 350D, and thought, "No, this can't be. How can I be having second thoughts? This is Canon we're talking about --- good ol' Canon. That camera company I was so sure of." Anyway, I picked up a D70s, and thought it felt much better. The D50 felt incredible. Anyway, I went home to do more research on the D50, and realized it was what I wanted. It took great photos, including under low light when compared to the 350D. Nikon also had several lenses that I really wanted.
If I had to go with another company, it'd be either Canon (not the 400D, but the 30D), or Pentax. I'll never be a pro, and I'm not a particularly picky person when it comes to superfine details (not even in my photos), so I think both companies would serve me well.