Get the 4670k. The only thing that the 3570k benefits more is from it's integrated graphics at 650Mhz vs 350Mhz and can overclock a little better. If you have your own dedicated videocard then no question, get a 4670k - newer technology, better performance in most applications, lower wattage, higher thermal limit, SSE4, AVX 2.0, etc..
Will also help 'future proof' you will Intel's Broadwell CPU's.