Navigraph data is far more complete and accurate than the stock MSFS data. I’m sure like any dataset, it has errors and omissions as well, but I’ve yet to personally find any, whereas I’ve found MANY in the stock data in the first few months after launch. It’s actually the shocking regularity with which I found missing or incorrect stock data that pushed me to subscribe to Navigraph in the first place. I haven’t looked back since.
I’m sure stock data has improved drastically since those early days, but seeing the number of posts on this subject that regularly pop up, I’m guessing they still have a long way to go.