It's a complicated question and if it must be condensed into a "Which is better and why?" question I'd say Nos was better.
It was better because the game had all the modern updates to the net code, the server could support well more than 5k people the originals did and Nos players had the benefit of knowing what is coming for patch notes.
Vanilla is the best game ever, but Nos was as vanilla as possible with modern tech. Long and short of it.