Depends. Are you a gear nut like most everyone here on TPF? If not, the D7100 will do you just fine, especially if you use your camera for stills. I have both the D7100 and D7000, and to be honest, I should have just bought the D7000 between this series of cameras. I do not shoot video, and they both take excellent photos when paired with excellent optics. When comparing specs, we're usually comparing gimmicks anyway, minus high ISO performance.
I was about to go out and buy a 610, but good guy has made me envious of his 750. I think this may be a hurt in the sausage ego department, but I have shot with both, and the IQ between the two isn't discernible to your audience. And let's face it, we shoot so that others can see our memories. I know good guy use to shoot the D7100. His Flickr has improved with photos from his 750, but to be honest, it's because he's become a MUCH MUCH better photographer since he got that thing.
It's not the camera. It's you. You just have to decide which gimmicks you want to pay for and how much you're willing to dish out.
I say go with the D7100.