Which camera is a better one?

I'm looking to save up for a new camera, and I want to get one off eBay, because it's cheaper. Which camera is better?

Nikon d5100
Nikon d3100
Canon 550d

The D5100 I think but getting it cheaper at eBay will be more expensive in the long run.

I believe the Nikon d5100 is.

Here is how the three cameras sensors compare

http://www.dxomark.com/...nd3)/Canon

As you can see, the D3200 actually has the most bang for the buck, having replaced the D3100

But of the three you listed, the D5100 has the best sensor performance