Upgrading: 3570k to 7600K or 7700K???

Right now I am running the 3570 at around 4.6 GHz. I am being CPU limited in Planetside 2 with my GTX 970 and as such think it might be time for a new CPU. I plan on getting a GTX 1070 which I will overclock and run at 1440p QHD using a 75Hz monitor. I plan to delid and overclock my new CPU regardless if it's a 7600 or 7700. Which should I get? I read that the 7700 doesent produce much benefit in most games over the 7600, but other things I read say it's hugely faster. Conflicting info...

Will you be upgrading your cooling as well? If you plan to overclock the new CPU then the Hyper 212 cooler will likely be a limiting factor on the overclock if you go with the 7700k and it may be with the 7600k as well if you push the overclock to the max. The HT will add some heat when overclocked. The 7600k will perform equally well in all but a very few games at the present time. That may change and likely will in the future.

Even at stock clocks either would be a big upgrade based on IPC improvements alone. I always go for the i7 variants personally.

Get the best you can/want to afford. I would no doubt go for the 7700K if you have the budget for it. Quad core is what I would consider a minimum these days for gaming honestly. Certainly you can use a dual with HT, but, performance losses can be seen... even with a quad no HT in some titles losses can be seen vs the 4c/8t part. I don't see the point to jump past 4c/8t for a machine primarily for gaming.