Haswell will have greatly increased graphical performance over Ivy Bridge, as well as a significantly lower tdp (power draw/heat output). Haswell will be released on June 3, during Computex 2013. The Sandy Bridge-E platform will still be significantly more powerful than the upcoming 4770k, but will draw more power, at 95w as to Haswell's 65w. I won't make that much of a difference power-wise, and it would be safer to go with the 3930k (or Ivy Bridge-E's 4930k) as Haswell currently has issues with pulling too "little" power and older psu's cannot handle the low voltages, causing the cpu to be unstable and likely shut down your computer. The benefit to going with the Sandy or Ivy Bridge-E processors is also that you get more pci-e lanes, a lot more processing power.
I also assume that you are doing video editing and stuff along those lines when you say "rendering," or maybe even 3D modeling or something, I'm not sure as you did not specify it, but, if you are doing any of this kind of work than going with the 3930k would help you greatly. If you did not know already, both the cpus you mentioned have hyperthreading, so the Haswell would have 8 threads, whereas, the 3930k or 4930k would have 12 threads. This does help, and any software that you would be using should be able to utilize all of this power, even if it is not fully optimized for it.
If you do end up deciding on the enthusiast level cpu (the E in SB-E means enthusiast), then I suggest waiting for a few months until Ivy Bridge-E comes out as it will have 20% better performance than the Sandy Bridge and much, much faster than the Haswell. One more thing as well, no matter which cpu you get, you will need a new motherboard as they all use different sockets, Ivy Bridge uses 1155, Sandy Bridge-E uses 2011 (I assume Ivy Bridge-E does too, but I am not certain), and Haswell will be very new, so there will mostly be basic boards, it uses a new socket called 1150.
I really hope that this helps, if you have any questions at all just ask, I will get to them as soon as possible. If you want to you can email me at (sytsma.austin@gmail.com), please no junk mail.
Austin