well its a hard question, many fanboys will be incoming defending their brands
But lets look it this way, now that you buy a PC how long do you think you will not upgrade?
AMD for now has better upgrade path then Intel because of Sockets and new technology, but intel still is little stronger in single core power (better for games) but AMD has more cores (not the 2 models you chosen but the next upgrade if you want). now to your choices they are both good CPU-s for lowend gaming, Intel i3 8gen is better over that AMD, but AMD is overclookable Intel if it doesnt have a K in the end isnt (and those Intels with K usualy cost more). i would recommend if you can wait to get the Ryzen 5 2600 if you want to overclock or i5 8400 if you dont want to overclock.