Pick your processor based on the types of games you play and your budget.
One guideline is to budget about 2x the cost of your cpu for the graphics card.
Some games are graphics limited like fast action shooters.
For them, spend more on the graphics card.
Others are cpu core speed limited like strategy, sims, and mmo.
For these, which tend to be cpu limited and single threaded, concentrate on fast single thread performance.
For them, a I5-7600K with an overclock is a very good deal.
As of 6/19/17
What percent of samples can get an overclock
at a vcore around 1.4v.
I5-7600K
4.9 72%
5.0 52%
5.1 27%
5.2 16%
5.3 samples exist, unknown % of occurrence
Ryzen is slightly less efficient per clock and tops out around 4.0.
If budget is not an issue, spend $100 more on a I7-7700K.
You will run near oc speeds at stock, get a better binned chip and 4 extra hyperthreads.
If you play multiplayer games with many participants, a high thread count fro ryzen processors is a good deal.
Then, consider your graphics card. Anything short of a GTX1080ti will play well with any $200 processor.
If your budget needs are more modest, look to a platform which can grow.
Ryzen is OK, but upgrading processors mainly gets you more threads, not faster single thread performance.
OTOH, a lga1151 based motherboard and something like a G6400 has a lot of upgrade potential.
Multiplayer with many participants tend to like many threads.