As usual,more useless graph wars,without asking the obvious questions. What games will be played?? What graphics card will be used?? How long does the build need to last?? Is an upgrade path in a few years an advantage?? I would prefer a Core i3 8100 or a Ryzen 3 2200G with a GTX1060 3GB or RX570 4GB over a Core i5 8400/Ryzen 5 2600 with a GTX1050 for instance.
If you are on a tight budget,and have DDR3,look for a used Haswell CPU,or even a Skylake CPU with a DDR3 board(will mean lower performance than in reviews with DDR4).
People on forums are the only people who care about a few percent here and there - unless you are running a £400+ card you are not going to notice the difference in most games with a Ryzen 5 1600/1600X/2600/2600X and a Core i5 8400/8500. I would even say compared to a Haswell Core i7.
I am still using an ancient Ivy Bridge Core i7 3770,and in almost all games at 2560X1440 I am still GPU limited with a GTX1080!
2666MHZ to 3000MHZ DDR4 is much of a sameness in price:
https://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007611 600561668 600561669 600561671 600052012&IsNodeId=1&Description=2666mhz 16gb&bop=And&PageSize=36&order=PRICE
One of the cheapest 16GB kits on Newegg now is a 3000MHZ kit. Same even in the UK.
Very few games actually need fast RAM - most tests are done at lowish resolutions using fast cards,and if you look at normal resolutions its not really noticeable in most games:
https://www.techpowerup.com/reviews/AMD/Ryzen_Memory_Analysis/9.html
https://www.techpowerup.com/reviews..._Memory_Performance_Benchmark_Analysis/9.html
Also regarding overclocking - the AMD CPUs have significantly better stock coolers,and the overclocking capable B350 boards start at £60ish and X370 ones at £70ish anyway,and even then it really does not do much as Ryzen overclocks poorly,so for many people its not worth the effort beyond what you could achieve on the stock cooler. That is from actual experience of doing some recent Intel and AMD builds myself,and they all ran fine with 3000MHZ and slower RAM,as again in the realworld it was worth spending the money saved on fancy RAM and coolers,on a faster graphics card,and even an SSD for specific games.