g4560 is best buy over i3 7100…get a g4560 and get a good dedicated gpu if you can with extra cash
you can also sell your old cpu mobo and ram and make little more cash for dedicated gpu
With the g4560 costing so little, like 60 bucks it makes no sense right now to buy an i3. Gaming performance is almost identical
If you are NOT in a hurry, wait for ryzen 3 and get a Ryzen 3… It should be out this summer. You have to upgrade your motherboard and RAM anyway and Ryzen 3 will cost as much as an i3 7100(assuming that the i3 7100s MSRP is 130$) and will be about only 5-15% slower than an i5 7600k which costs 250$. It will also give you more time to save up more money.
Otherwise if you wanna insta-buy those awful dual cores, get the pentium g4560 as it's only 5-10% slower than the i3 7100 while costing 50$ less.
buddy i will recommend corei5 6500.
i3 are not good for high end gaming