Facts first.
Assume, for comparisons sake, that the Ryzen+ CPUs have a 200MHz Speed bump, which is nice, but will not decide the war.
The question will be, "How mich GHz per buck", and "Will it be enough GHz for my resulution?"
The Ryzen 3 1200 - sorry to spoil your day - isn't even worth an upgrade from socket AM3+, if you consider it's price... Only starting with the Ryzen 5 1400, AM4 beats AM3+ with the AMD FX 8350, for any FullHD-Gaming. As the price is not that much of a difference, the Ryzen 5 1500X is just better. But we are already in the €150 range here.
If you are in serious gaming, 6-core is the "sweet spot", the cheapest 6-core is the R5 1600, and that will remain true even when Ryzen+ comes in, even more, if you consider overclocking.
So, it is a question of budget, and that alone.
Sort all other 6-cores from AMD by price, and take the one you can afford.
If even the R5 1600 is too expensive for you, get the most expensive Ryzen 4-core (Ryzen+ or Ryzen) you can afford at the time you buy. But wait for the Ryzen+ to come out first. It's a simple as that.
Everything, starting with the Ryzen 5 1500X, is just much better than the Ryzen 3 1200, and you will feel that.
It's worth checking the support-pages of the MoBo you own, to see if any Ryzen+ BIOS update is planned. If not, the question does not come up. If the AM4-MoBos don't all of them support the new Ryzen+, AMD will get cornered by their fanboys, as that was - and hopefully is - a major factor for AMD being superior regarding budget.