I use a resident program called Nutribase, which is a slightly lightened version of what they sell to doctors and RDs (lightened mostly in that it can only handle a few "clients" rather than hundreds) as any of the online apps when we started this around fifteen years ago sucked, particularly when trying to handle menus for more than one person.
These apps are only as good as the databases they use, typically USDA and the manufacturers, (Nutribase also draws from Canadian gov databases, as well), so one product is unlikely to be any more "accurate" for what you are looking for than another.
If you are worried about how net carbs are being calculated, you are way overthinking the problem, as that has virtually no impact on your WLS success. The fiber is important to keep track of to help keep things moving and the overall calories largely govern your loss rate. For the rest of it, learn to eat good quality food and the rest pretty much takes care of itself. With things like carbs ( and fats, when that was the big diet thing) quality is a lot more important than quantity. 60-70 g of high quality complex carbs from fruits, vegetables, whole grains, etc., is a lot better for you than 20-30 g of junk carbs from artificial sweeteners and frankenfoods.
Note - I never worried about carb and fat counts and still had to slow down my loss rate as I got to the six month mark.