Nimzowitsch Defense or Owen's Defense?

Which is more legit and why?

Nimzo and Owen have totally different mainlines. Maybe, it would be more meaningful to compare Owen and QID.

M

Both are VASTLY INFERIOR to e5, e6, c5, or c6

Owen's defense sucks slightly less than Nimzowitch

Both 1 e4 Nc6 and 1 e4 b6 are playable.

Nimzowitsch is better, except that there’s effectively no point in playing it. The Declined transposes straight to e5, and so more than 3/4 of your games will be in that, and at that point just play e5, y’know?

Owen’s is worse, but easier. Who knows, you might even get some good wins against people who don’t know how to refute it. That being said, I sincerely don’t recommend it.

I crush nimzos without even trying and hate the owens so much I created a naselwaus gambit book to combat it.

Take that for whatever it's worth

Nc6 is actually pretty good. Even nf6

Hi!

I prefer the Owen Defense. When I was working on a speed chess repertoire a couple of years ago I tested the Nimzowitsch Defense and I was not satisfied with my results: 38% wins, 10% draws, 52 % losses from 29 games. Then I tried the Owen Defense and had much better results, over 50% wins, so it became my main defense against 1. e4, with more than 1900 games so far - I can say I have experience with it!.

I think the Nimzowitch's can lead to too many different central structures (i.e. Scandinavian, French, Advance Caro-Kann...) while in the Owen's you just fight against the ideal center (pawns on d4 and e4) - it is more thematic I should say.

Good luck!

If legit means soundness, then definitely 1...Nc6.

2.d4 d5 is so legit that even GMs in classical games chicken out and just play 2.Nf3.

Most of the people saying 1...Nc6 isn't good probably don't even know the correct way to get an advantage with white. 2.d4 d5 3.Nc3 gives white nothing. Probably the Advance 3.e5 is the only way for fight for an objective advantage.

As far as I can tell, 2. d4 is ever so slightly inaccurate, and White either has to play 2. Nf3 or 2. Nc3 for an advantage.

If that were the case then 1...Nc6 would be equally strong as 1...e5 as a first move, since both moves transpose with best play. 2.d4 is the only attempt to prove that 1...Nc6 is suboptimal.

Yes and no. I do believe that 1. e4 Nc6 2. Nf3 e5 is almost (if not equally) as strong as 1. e4 e5 2. Nf3 Nc6. However, it gives White options that he wouldn’t otherwise have, and Nimzowitsch positions (in 2. d4 and 2. Nc3 along with sidelines) are rather difficult to play and almost as a rule objectively sound for White. You won’t get a large advantage in almost any of them, but you’ll retain a small amount or at least in equality in all of them, and they’re quite difficult to play as Black.

Is the Nc3 line hard to play as black?

Both are amazing.Why choose between them? 
Only reason Nimzowitsch defense is not seen more often is that there is no consensus on how to play vs 2.nf3 in a way that doesnt just play 2.e5 and transpose. Although its clear to me the "nimzo-pirc" approach is by far the best approach .
Owen's just greatly understimated . Black must be confortable in creating counterplay with less space

as others have mentioned, in the d5 nimzowitsch (not to be confused with 2.nf3 d5?! which is dubious) only 3.e5 seems to give white any real advantage. But what's really telling is that the average master would rather play 2.nf3 and "risk" allowing black to play a ruy lopez/italian/scotch including lines like the drawish berlin defense, then to prove advantage via. 2...d5 e5 in the advanced nimzowitsch. Its pretty curious since the eval for the advanced nimzo is usually modestly higher than the most main line double king pawn defenses. 
What this tells you is that most masters dont trust the engine too much. blacks familiarity is deemed too big a treat, that they rather transpose to safe territory. Remember that masters value white's first move advantage a lot more than amateurs which is why 2.nf3 being more common than 2.d4 is so surprising.