well apparently the 'ph perfect' stuff is an improved formula, but who knows what that actually means and whether it counts for any discrepencies. the water here does tend to be a bit on the hard side as well, which may counteract any deficincies that might've been noticed elsewhere.
as for the original point of this post, what is better GH or AN, and i don't think either line is BEST all the time, they both fill different voids in the same market - and which one is best really depends on the grower and the situation. if you don't mind buying a few extra bottles (which
will last longer anyway), and are good at tinkering with your formulas, then i have no doubt that GH (or any other brand) could be used just as well in the hands of the right grower....
but if you're a surrogate grower (someone with a bunch of plants in a location that isn't your residence), and you only get a span of an a couple hours a week to maintain everything, than being able to use direct tap water and not dick around with ph/ppm is ideal.
also if you are a new grower, who is still feeling out hydroponics, and you
haven't already spent a money on ph-adjusters and a ph meter (and/or ppm meter), then i'd highly recommend the PH-perfect a&b, simply because it's still cheaper than buying a comparable competitors product
and the meters/adjusters, and for someone new this will let them feel out hydro without the downside of playing PH god (which too many rookie growers do, they neglect PH, or they over-compensate checking it all the time, driving themselves and their plants crazy).
furthermore, sometimes there are people who are experiences growers, and they simply buy the AN stuff for the ease of use with a complete base, and no formula tinkering.
however, if you are doing a perpetual grow, are used to the plants you are growing (and the style of growing you are doing)... in other words you are 'dialed in', and can perform the same results with GH (or any other brand) for cheaper, than you'd be stupid not to.
but again, these products, at least in mind, fill in different gaps in growing situations. there is scenarios where i'd prefer to the ph/ppm perfect AN stuff to anything else, and there are other scenarios where i'd rather tinker with my formulas and save money using another product.
i think it's kind've like using an Apple PC vs a Windows PC, with
advanced nutrients being Apple and GH being Windows. apple has more marketing, does work really well and is especially great for new-comers, there is little things you can do to fuck up an apple computer, but they are expensive. Windows is a bit more generalized, you can do just as much stuff on a windows computer, but there is a bit more troubleshooting, especially for rookie users.