Which one of the DO YOU PREFER?

I'm planning to purchase a DSRL Camera!
My choice is Canon!
Guys, Tell me which 1 should I buy?
Canon EOS 550D (or) Canon EOS 60D?

If you want you may include Nikon D3100 into the discussion.

Please do specify your reasons.

For a starter you go for the least expensive ones. Its not much about the model, it's more about the lens and what sort of things you want to capture with it. You have to get to know the camera and all the things it is capable of doing and then see it from there. Whether you get a new one or just the lens or ad few accessories to it. Just put in mind that If you invest in these kinds of cameras, you might as well think of investing more time to it to make it worth the money spent. I myself have one but with a full time job, I hardly have any time exploring much to it. I just end up using the basics and buying the compact version of it because I find it really bulky and heavy. I'll only bring it in really serious getaways to get good shots but for regular parties or certain events, nah, not keen to bring my dslr.