I think the main difference between HQ and AHQ are not the rules. It is their quests. In HQ you have a bunch of interesting quests to play, and a lot more with the expansions. They are so many that if you play all of them, you have learned so many things that easily you can create your own. In AHQ the quests that comes with the box are terrible. I believe they’ve made them so simple because they want to encourage the players to create their own, or to show that it is very easy to have fun even with simple quests. Of course the problem is that no one teaches you how to create interesting quests.
Other things that does not add anything to fun, is the initiative, the sentries, the doors that can be opened from monsters, the traps which are tokens that GM can use at will and not placed on the board like HQ for a reason, the death zones (the only thing I like and HQ does not have is the critical hits and the fumbles). I can’t understand why they’ve put all these. The combat isn’t more interesting than HQ’s. Even the tiles have no meaning… Who said that in HQ you can’t create very different dungeons by adding blocks or putting extra tiles on the board?
Of course a very experienced GM can create excellent quests in AHQ, like HQ’s. And the rules are not a problem, they just slowing you some seconds... It’s better than WHQ, so for me is the second best boardgame ever.
By the other hand, HQ has narrow rooms and one-square-width corridor for more tactical battles. With narrow rooms even the furniture adds to the tactics of the battles. Another plus is that you can create quests so easily that you spend more time to create the story and less to put the rooms and the monsters. But the most of all is that its system is so well balanced that it’s very hard to bend. Also, with so many monsters you can create your own by saying “it should be strong like orc and not like chaos warrior, so it should have Attack 3”.
I could talk for hours for the goods of HQ but you’ll find soon.

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