Ryzen 7 1700x vs Intel 7 7700k

Solution
It really comes down to what monitor you'll be using - if you will use a high refresh rate monitor, i.e., 144 Hz or greater, then it's best you wait till October 5 for Coffee Lake CPUs to launch, and get an Intel i7 8700K. If you will be using a 60-120 Hz monitor only, then a Ryzen 7 1700X would be the CPU I'd recommend.

This is mainly because high refresh rate gaming requires strong per core performance, which is found mostly on Intel chips. For a 60 Hz monitor, you don't need very strong per core performance, so a Ryzen CPU is also sufficient. Since a Ryzen CPU has better value and more cores for the same amount as an Intel chip, Ryzen CPU becomes the better choice for a 60-120 Hz monitor.

So, depending on the monitor you have...
It really comes down to what monitor you'll be using - if you will use a high refresh rate monitor, i.e., 144 Hz or greater, then it's best you wait till October 5 for Coffee Lake CPUs to launch, and get an Intel i7 8700K. If you will be using a 60-120 Hz monitor only, then a Ryzen 7 1700X would be the CPU I'd recommend.

This is mainly because high refresh rate gaming requires strong per core performance, which is found mostly on Intel chips. For a 60 Hz monitor, you don't need very strong per core performance, so a Ryzen CPU is also sufficient. Since a Ryzen CPU has better value and more cores for the same amount as an Intel chip, Ryzen CPU becomes the better choice for a 60-120 Hz monitor.

So, depending on the monitor you have, you'll have to decide yourself as to which processor is better for you - Ryzen 7 or the upcoming 8700K. Avoid the 7700K, it isn't as future proof, and a quad core will really be the entry level for gaming in some time.
 
Solution
If it is just for Gaming, then the 7700K, though I would wait 2 days for the new 8700K reviews as I believe that will match the 7700K, overclock a little better and provide 2 extra cores allong with threads..We are talking about 4.7Ghz single core boost out of the box and 4.8Ghz overlcock on all cores..if that turns out to the case, then it should be a doozy for gaming..

The Ryzen is also a good choice, especially if value is more of a concern...