I like the 375 Flanged but it depends on what you are going to use it for. The 375 should be quite a bit flatter and may be classified as a 300 yard rifle for Deer, Elk etc.

I do not know how flat the 400 with the 300 grain is but the 400 grain is, at best a 200 yard rifle.

If big animals are on your plate than the 400 is pretty hard to beat.

I like my combo of a 450/400 and a 9.3x74R.