I simply disagree. I think machine Y can be better than machine X at a particular task.
When I started, the war was between the E-Trac and the V3i at the task of finding silver coins. When it was clear as day that the E-Trac was better at that task, V3i defenders would never admit that, they simply would hide behind the quoted line: "you don't understand the V3i".
Whatever. Life is short, and time is precious, and I wanted to spend it finding silver coins, not learning some arcane machine programming to find the same coins the E-Trac could find out of the box (my day job was to program machines, so not only am I not an idiot in that regard, I didn't want that for my hobby).
But, I went a step further. I was fortunate enough to be able to afford both an E-Trac and V3i at the time (hint, buy used), and compared them head to head on the same targets. The E-Trac was simply better at the task of finding silver coins (it wasn't even close), and no amount of arcane programming of the V3i could change that.
I've never used a NOX, so can't answer the question directly, but if the claim is true that the NOX is better than the E-Trac, it is likely better than the V3i.
Now, some of it comes down to taste -- what about the tones, the screen, the weight, and so forth. These things might be important to some people, but I say go for the best machine, and learn to live with annoying taste issues. The E-Trac, for example, is heavy and not balanced well. But that is something I learned to live with as for me, being reasonably physically fit, it was just a taste issue.
Good luck
I absolutely agree that machine X can be better than machine Y at specific tasks. That is one of the excuses I've used for having more than one machine (I try to have machines that compliment each other while also excelling at a particular task that I deem necessary). The truth of the matter (though) is that I just like trying out different machines that catch my fancy.
I also owned an eTrac while owning a V3i. For me the V3i was the better machine; I found more silver with it and enjoyed using it far more. I actually did like the eTrac (loved that silver warble) but it wasn't balanced very well and I just preferred using the V3i. I sold the eTrac and bought the CTX 3030 (local dealer convinced me that it was the machine that I had to have). I didn't care for the CTX 3030 at all - the balance was better than the eTrac, but it just wasn't the right machine for me, so I sold it as well.
I don't know if the eTrac is the better machine (verses the V3i) or not. I do know that the V3i was/is the better machine for me. Obviously I am in the minority there but given my own experiences (with different machines) I have to think that personal preferences play a vital role when it comes to which machine is the best.
I believe that the reason I found/find more silver with the V3i is because I like that machine better - it fits me well and I just happen to gel with the way Whites machines are set up (I love my MX5 as well). I like all of the machines I currently own, but have the most time on the V3i and the MX5 so I naturally have more confidence when I'm using either of those two machines.
Are there better machines available (than the V3i or the MX5)?
For some specific purposes.... Absolutely.
In general?
I don't believe so. Not yet anyway.
That's not a slight against all other machines - I am quite sure that if I had gelled with either of the two Minelab machines that I'd think (for me) that machine was the best machine for me.
I know I miss stuff with both the V3i and the MX5. I also missed stuff with the eTrac, the CTX 30303, and miss stuff with every machine I own. I know that because I've gone back (time and time again) to the same places with each machine and have found stuff with every machine. I've found stuff that others have missed and I'm sure that others have found stuff I've missed. Maybe I wasn't paying enough attention to those faint sounds, or maybe I just didn't get the coil over that particular spot?
Is there a best machine?
I suppose so. Maybe?
But I think the real question is "best for whom"?
Some swear the Equinox is the best machine. Others say the best machine is the Deus. Then there are those who say the AT Pro/Max is the best machine, or the Fisher F75, Teknetics T2, Whites MX Pro, Tesoro Vaquero, Nokta-Makro Anfibio, etc...
I think they're all correct - for themselves.