As you're coming from a 400D, in your sig, then the 650D would be an ideal replacement for you. You're already used to the layout of it as it's similar in size and ergonomics to the 400D and it's got a very good set of features.
The 60D, on the other hand, with give you the rear dial and top screen which I much prefer as I find it quicker to set up for the shot. The features in both of the cameras are very similar, I think there's a 1 stop difference in ISO between them, and the 650D has the touch screen and the ability to use the STM lenses for video work. I swapped my 60D for a 7D and TBH I found the pics SOOC from the 60D are cleaner and less noisy than the 7D. A 60D with a 7D AF system would be great. The wife has a 650D and loves it. I said she could have my 7D when I get my next body but she wants to keep the 650D instead.