It amazes me that this topic keeps coming up on internet forums.
Null means Null. Identical. There is nothing different. If it actually does null, then you aren't hearing anything different. Your mind might think so for psychological reasons.
Now that being said... aside from a very controlled experiments with test tones, I find it highly unlikely that anyone was able to mix an actual music project in two different DAW's and get them the actually null. If they say they did, I don't think they know the meaning of the word "null". There are too many factors for why it would be utterly improbable that anyone would ever mix down a project with all the various plugins and faders...in exactly the same way in the two daw's leading to a null result.
So yes..its possible that you mixed a project in one DAW and liked the sound better then the other, but based on scientific evidence that has been tested countless times in the past few decades, that is not due to some fundamental DAW voodoo...its simply the way you mixed the project in each DAW.
I have never seen anyone actually provide sound files of two mixed projects from two different daw's that actually do null. I find it highly unlikely that anyone has ever been able to do that. But also many simple tests with test tones between two DAW's have been done, with perfectly nulled out results....meaning...exactly the same result. This is scientific. If you deny this science, then I can't help you, I'd suggest getting a voodoo doll to help you with your mixes then.
But it also has to be recognized that people work differently in different environments and one daw may very well lead someone to create better sounding mixes then another daw, simply because of the way they are using it...but that is entirely subjective, any DAW can produce absolute magic in the right hands.
All of that being said...admiral bumble bee also has measured scientifically the differences between DAW's while performing automated fades. So if your project has a lot of automated fades happening....(not midi fades)...then definitely all DAW's are not created equal. Unfortunately, in that test, Cubase didn't fare any better then LogicPro in terms of intermodulation noise. But then...maybe you like the Cubase flavor of intermodulation noise.