All three would be good...one thing to think about is how long you want it for, if planning for two/three or more years then I'd go to the 4670K it's newer doesn't cost much more than the 3570K. If for the same rough time period and a tight budget, the 3570K has near same performance (maybe about 10% less, but it and the 1155 mobos costs a little less...If only thinking 1-1 1/2 years the used 3770K is a interesting idea idea, most powerful of the three, runs hyper threaded apps, mobos are reasonable (same as 3570K), I wouldn't normally throw this in but if thinking the shorter term, then you'd prob be looking at Broadwell next year....and if things stay on track.....it will prob be DDR4 instead of current DDR3