An i7-4790K would double your thread count, and increase clock speed, but, as that CPU is the end of the DDR3 upgrade path, those CPUs are not cheap. As long as your chosen games are at least playable now, perhaps you can wait a month or two and see what the new Ryzen 3000 series might be bringing to the proverbial 'gaming table'... (Any more significant upgrade will require stepping to new mainboard and DDR4 RAM as well, of course....)
The i7-9700K and Z390 are quite popular, although many are alternatively choosing the R5-2600X/B450 mainboard path...