Which is better for gaming
Strictly looking at performance the 3600 but its not by much at all.
Price to performance heavily favors the 9400F which depending on title selection trades 0-5fps on average for costing less then 3/4 the price with its price cut.
But then again you also have the 2600 for 2/3 the price of the 3600 that is only 10% behind the 3600, so it isn't just Intel gutting the value of the newer models.
hopefully next generation the i5s with Hyper Threading inherit the price-performance of these
Strictly looking at gaming price to performance I think the I3 are poised to take the cake with $100-$120 7700k performance.
Intel confirmed all future "F" models will be at a lower price, so the 9100F replacement is going to be a budget powerhouse.
Apart from gaming the I5 with 8700 performance are going to be very competitive, its only in the high end that I think Intel will struggle.
That might actually lose AMD some of their customer base interestingly enough since their almost cult following has always been about the budget range.
while the i3 10100F(?) is going to be a powerhouse, the i5 10400F(?) is going to really shine against the Ryzen 5 3600
What they really should do is offer two models.
One with no cooler.
One with one of the M9I/Pure Rock Slim knockoffs for an additional $10-$20.
I would usually be advising Ryzen 5 3600X considering overall package including cooler but looking at the price of the i5-9400F, one vendor @ $128 makes me rethink whether it is worth prioritizing performance over cost. The i5 is a very reasonable choice for a gaming CPU even at it's original MSRP. At six Benny's it is almost a steal.
A sub $500 somewhat decent gaming PC is within strike zone nowadays with the RX 570 being a value proposition at the same price.