Not enough performance difference between 1st and 2nd gen Ryzens yet. Maybe 3rd gen will change that. I'd opt for the 1600X (budget-wise speaking) since it is the same price as the 1600. The 1600X is slightly faster out of the box than the 1600, and may be a higher binned chip if you intend to OC.
well if you could wait a bit longer Ryzen 3xxx lineup is coming up around june/july this year so you might get more bang for your buck by then, and if the performance gap isnt too high for your taste it would be safe to assume that the prices of Ryzen 1st and 2nd gen would drop so you could get them and free up more budget for other parts of your build/upgrade.
The 3rd Gen Ryzen is what I'm waiting for to replace my 1st gen platform. But I'm afraid the 3000-series Ryzens will be top dollar and scarce for quite awhile; not exactly a bargain when they are first introduced.