Nikon 200-400 f/4 vs Nikon 300 f/2.8? Better option?

As an owner of both the 300 f2.8 has an AF speed advantage when that is important.

Nikon's MTF show at 400mm it is easily the best zoom in production, scoring very similar to the 600 f4

Although Thom Hogan reported sharpness issues at longer distances, contrary to Nikon's MTF, I do not have any issues in good light at 1-2 miles distance.

It is fair to say in low level, low contrast light an f4 lens stops locking on before an f2.8 lens, and with more air/glass surfaces than any other lens in the Nikon range the zoom has slightly lower contrast than the prime.

--
Leonard Shepherd
Many problems turn out to be a lack of intimate knowledge of complex modern camera equipment.