i5 6600k or i7 6700

Solution
I would go with the 6700, unless you like the idea of overclocking.

An OCed 6600k will have better single threaded performance, meaning it might perform slightly better in some games. But the 6700 is already around 4GHz which will still provide excellent single threaded performance, while the extra threads have the potential to make a greater difference in applications that can take advantage of them.

TJ Hooker

Titan
Ambassador
I would go with the 6700, unless you like the idea of overclocking.

An OCed 6600k will have better single threaded performance, meaning it might perform slightly better in some games. But the 6700 is already around 4GHz which will still provide excellent single threaded performance, while the extra threads have the potential to make a greater difference in applications that can take advantage of them.
 
Solution

neblogai

Distinguished
Wait a month or two if you can. New AMD Ryzen processors will be released in 3 days, but these will be high-end R7: 8-core models with prices $329 and up. A month or two after them will come R5 models- 4core/8thread 1400X at ~$200, which should be speed-comparable to 6700, and 6/12 1600X at ~$260 which is even faster. Also, they are all unlocked, and can be overclocked with B350 or X370 motherboards. If you are interested- follow the news- reviews of R7s are to be released very soon, on 2nd of March, hopefully with more news on R5 release as well.