In the general sense, yes.  But in the particular case of 1 Nf3, there are a limited number of candidates, and their advantages and drawbacks are easily seen.

The main replies may be seen as ...Nf6, ...d5, ...c5, and ...g6.  Secondary replies which may also be viable are ...e6, ...d6, and ...Nc6, none of which can be called objectively bad but do not assert anything either, given the flexibility given to Black.

1 ...d5 cannot be bad, but it plays into a likely White hope for the Reti.  The Reti is certainly no threat to Black with good play, but disallowing a likely White intention is worth something.  Scratch it.

1 ...c5 likewise is solid, but allows White a great variety of choices.  Again, it cannot be bad.  But it doesn't develop a piece or enable development.  1 ...g6 enables development of the Bf8, but commits to the fianchetto. 

1 ...Nf6 develops the Knight to its optimum square and retains all flexibility.  It is therefore the best response, logically.  And it is clear that no other move can be demonstrated superior to it.

I agree with Nf6 being the most flexible and solid answer to Nf3 (along with d5).  The only inflexibility I see in Nf6 is that an early f5 can't be played, so a Dutch player would probably want to choose f5, e6 or d5 instead.  I always play Nf6 against 1.Nf3, 1.D4 or 1.C5 though.  I can transpose into a number of defenses with that.  

Is there any famous game started with 1.Nf3 Nf6?? If yes, can someone post a game here?