By now, I think the difference in authenticity between the competitors has decreased strongly.
I agree. I suggest it also depends very much on the player and how well he can emulate the nuances of each instrument.
No matter how good the sample (including VST's), a good part of the
perceived realism still depends on the player's skill, and, although great strides have been made in achieving authentic
articulation (SA/SA2, DNC, SuperNatural etc.), a trumpet sound, for example, will not be realistic if the performer doesn't allow for breathing and doesn't play in the proper range.