Having mainly built Ryzen systems of late, bit out of touch with the confusing Intel multiple chipset world.
But if I were to build a gaming system around the i5 9400f, which chipset is best suited?
Well Z390, Since there are many options, I would suggest you to look which extra "stuff" do you need, like extra PCIE, USB 3.1, Type C ports.
But Asus Z390 A looks fine for me, but others more Experienced would suggest you better.