The AN guys come off as really sleazy used-car salesmen, IMO. That being said, I've never used their stuff so I can't comment on the performance. I can, however, comment on their nutrient challenge that's all over youtube. I think their biggest competitor is GH and in their challenge, they are missing half of their expert line. Maybe they weren't available back then but they're missing liquid kool bloom and kool bloom dry, floralicious plus, flora blend and flora nectar. I also find it interesting that they do not show you EXACTLY which AN nutes they're using.
Regardless of my personal impressions, I think any of the reputable nute companies will give you a stellar product but the trick is learning how/when to use them. Personally, I use botanicare in dirt and GH in hydro. I use 6x600hps and easily yield a pound per light per 2 months.