You need to really test these things instead of asking, I know it can be a little difficult to do this but the fact of the matter is you will always be told to buy more from people on the internet, because 99% of the time it is a random thinks-they-know-it-all and they will tell you 8 or 16GB isn't enough.
It is your needs that are important, and do not let a bunch of strangers on the internet dictate your decision. For reference, I use to use an 8GB MBA with Edge, tonnes of extensions, tabs opened at once, photo editing, video consumption and gaming and it didn't skip a beat, it was a tank. I would have not noticed an upgrade to 16GB. That was just my experience, yours may differ so it is important to test these things if you can.
Apple offer a great 14 day settling in period, use it to your advantage.