Marvel, or DC?

I've noticed that tendency among comics fans, that they tend to have a strong loyalty and enthusiasm for one or the other.

Despite that I myself fall into that category, I've always found that tendency rather odd, since many of the same writers, artists and editors have worked for both companies, or even freelanced for both simultaneously.
Even so, I've always been amazed how different the feel is to the work produced by Marvel, vs. that of DC.

So which do you identify with most? What about it resonates for you?
And within whichever you do, what era of work from them do you like the best?