Okay, my 15-20 cents.
Models: These models are the best of any wargame I've ever seen. They're sharp, well designed and cut, and the kits are easy to work through. Really top notch work.
Lore: GW has always had the best lore teams on the planet, and it's really coming together now that they've had some time to breath in the mortal realms. I really love the work they're doing there.
Release schedule: I love that every other week I've got something to look forward to and read about, and a new kit to add to my dragonpile of unbuilt stuff.
Warhammer Community: While not totally AoS centered, warcom is like, the best thing to happen to GW. I imagine it's only a matter of time before they bring back the GW forums again, like that had when I was a wee lad.
Balance: While I feel AoS is probably the most balanced wargame I've played before, I feel it suffers from two major balance issues. Internal balance in a faction, and a "rock, paper, scissors" mentality. The first is simple, some units in books are vastly worse than other units in the same book, for the same points. Some artifacts are flatly better than others. Some subfactions are insanely better than others. The latter issue is a much harder problem. GW has always had a "rock, paper, scissors," mentality. It's fine for DoK to be an insane synergy faction that can kill anything they touch, because they're weak to shooting. It's fine for OBR to be functionally unkillable, because they're slow and can be out maneuvered on the board. It's fine for Skaven to cast infinite spells a turn, because they have weak units that die like gerbils in speed bags. The problem with this mentality is that in a game like this, that has a high barrier of entry, walking into a local meta that is full of paper, when you've got a bag full of rocks, feels bad. It doesn't matter how much I love X faction, they're seriously countered by Y faction, and my main opponents play Y.
How do we fix this? The solution to this is something that most people won't want, but it's to make armies more milquetoast. Don't let a faction's theme being models are unkillable, or can punch someone into the sun. Make a unit that is "good" at combat 3 by 4, with 1 rend. Make a unit that is "tanky" 2 wounds with a 4+ save. Now you won't have that insane skew that leads to the rock paper scissors design.
Play-testing: This leans into balance a little bit, but it's less about power and more about consistency. I play a lot of games, both physical and digital. One of the best things that many developers of digital games do is release a PTR, or public test realm, where you can play-test the various changes and updates. I know part of the magic of GW is the fact that you don't know exactly what's coming, and things are kept under tight wraps, and the rumor engine takes terrible pictures of them to make us argue if that scaly bit is an elven cloak or a seraphon character (it was a chaos mount in the end, go figure.) But the down side of this is that the small hush-hush community of players that get into play-testing suffer from a few major issues that leave books in a sorry state where they need an update a few days after launch. Firstly they are a small enough group that not enough feedback can be given. It turns out sometimes you just need monkeys with typewriters, and not hand selected specialists. Secondly, the hand selected specialists aren't actually very good at the game. Personal side note, I played against one of the guys who was on the play-testing team for GHB2018 at adepticon, and he didn't know the rule about being able to pile in if a unit charged, and its target was wiped out. I used that trick to win the game, and he called a judge over, who just looked at him funny and then pointed his name in the book out to me.
How do we fix this? Simply have a larger group of play-testers, and also have a more selective group of "top tier" play-testers. Consider the following: The current core of testers now get the book a year in advance, as they currently do. They muck around with it, they give feedback, changes get made. Then, 2nd pass comes in 4 months later. It goes to a much larger pool, basically the public, who then does further play-testing, and gives further feedback. Suddenly you have a much larger group who is funneling information back to GW. And hell, even release the models in that 2nd phase of testing, so you don't have to worry about copywrite issues. And if they wanted to be really cheeky, they could have people pay a small subscription fee to get this play-test material every time it comes around (which at the current release rate would literally be once a month,) and that would give them a steady stream of revenue and would mean only people who are really dedicated to the program are giving feedback.
Terrain and LoS: True line of sight is bad for the games health. It's cinematic, it's very easy for a new player to understand, and it moves the game along very quickly. The problem is if you have two players who disagree, it becomes hard to have a hard and fast ruling, and it also makes it hard to release cool and ornate scenery pieces, because people will argue about how they effect line of sight. The other major problem with terrain is the rules for placing models. I see games all the time where people just gingerly set models that clearly don't fit and say "well he's flying, so it's fine." It bothers me, and it looks bad.
How do we fix this? Firstly, make the base rules official, and not a suggestion. It's time. People have had their square bases for long enough. Secondly, assign every base size a "size score" between 1 and 10. Do the same for all terrain. If something is bigger than you, it blocks line of sight for you. Done. For the flying thing, have a simple rule added into the matched play section. "If it fits, it sits: A model can only be placed on a section of the battle field large enough to hold the entirety of its base. If any portion of the base is unable to sit flatly on this section of the battlefield, weither by hanging off or sitting at an angle, it can not be placed there." Easy money.