Hey NoBarriers, don't let the negativity get you down. Unfortunately you get used to it after awhile (if you haven't already). The internet allows everyone to voice their opinion if they want to, and if you can say it often enough you can build the appearance that you know what you're talking about (not saying that anyone in particular doesn't know what they're talking about, but simply that what appears to be the voice of experience is not always the case).
Right now it's popular to hate Advanced Nutrients. Those of us who've been around long enough remember when the opposite was true. Now in my opinion, and I'm certainly not alone in this, the only thing that's happened since then is the company has gotten better at basically everything they do, including marketing. That, and ragging on AN is what the "cool kids" do, so a lot of people do it for no other reason than they want to fit in.
Anyway, more to the point, there's absolutely nothing wrong with using Advanced Nutrients. If you get good results with something by all means use it again. If someone else gets good results with something else it doesn't change the weight or quality of your bud in the slightest if you can make them feel unhappy about their choices.
Unfortunately many people never seem to learn the whole "more flies with honey than vinegar" thing and instead like to use sweeping generalizations like "people who use Advanced Nutrients" combined with insults like "are naive, stupid, etc." If I wanted to warn someone about a nutrient company I personally felt was bad (say Dyna Gro, just as an example) I would first make an effort not to paint every Dyna Gro user as a moron because that would immediately create an adversarial relationship.
If someone actually wants to help you, they won't be a douche. If someone just wants to spew out negativity, start an argument, or otherwise be a douche... well then that's the way to do it.
In short, don't sweat the haters. They hate everyone who isn't helping spread the hate.