I'd go with the 600d or the 60d. The 700d doesn't offer much over those two. It has better focus during video with STM lenses and comes with a new kit zoom. While the the improvement on the zoom is nice, it isn't worth the price. The sad thing about Canon is that the sensor in the sensor hasn't changed since the original 7d (sept 2009), 550d(feb 2010) and 60d(aug 2010).
This means that you should expect to get basically the same results from all of Canon's crop sensor cameras (excluding the 1100d series which uses another design). The main thing that changes between these cameras is the AF system, the viewfinder, the build quality and burst rate.
The 600d was a nice upgrade to the 550d, tillable screen and better AF. However, the 650D only brought better live view AF which isn't all the useful. And as far as I can tell, concerning the body, the 700d only brings creative filter that are previewed in Live View. Which is probably useless for most. However, it will come with a better kit zoom lens.
The 60d offers quite a bit over the 600d and 700d, better build quality, better button layout, better viewfinder and a much better burst rate. These might not seem like much but make the world of a difference if you're using your camera every day.
I won't bother telling you about the 7d, it's out of your price range but it's basically a pro camera, it's built to last, resists to weather, has a ridiculous burst rate and much more advanced focusing system.
Also, in your last posts you keep mentioning the 6d. I'm not sure if you're doing a typo and mean the 60d or really talk about the 6d. The 6d is a very different beast to the bodies I mentioned above. It has a much larger full frame sensor. It sets it in a different category, it can only use EF lenses but has much better image quality (to keep things short). Much better camera, but much more expensive too.
IMHO, the 600d and 60d are the best buys. However, Canon is expected to launch an upgrade to the 7d/60d and this will likely come with a new sensor that will probably then see trickle down to the 750d. Those cameras will probably have better image quality (resolution, low light performance, dynamic range). That being said, the more you wait, the more the price on the 60d will drop. The 60d is a better choice over the 600d if you'll be using your camera every day, shooting a lot and see more use. The 700d doesn't really bring you anything over the 600d and 60d, you might as well get the older bodies and trade that name plate for some shiny new lenses.