Today's games run well with 4 fast cores according to 3300X reviews so if your happy playing today's games then go for the 3300X.
However, the 3300X will struggle with future games. That's a fact. So if you want a CPU that will last a few years, get the 3600X.
The 3300X is a good temporary CPU to tide you over until Ryzen 4000. It's not a permanent CPU if you're a gamer.