We always did DHT or CoS because normally they took ~12 minutes and you could find keys a lot faster. No use spamming Maw if literally everybody else is spamming Maw because they think it's the only fast dungeon to do. DHT is actually insanely fast and easy, I avoid it on teeming weeks though because it's one of the more affected instances in regards to teeming count.

CoS is a lot faster than people think, even with the RP. There is some RNG, but if you're doing it for AP farming you don't really go out of your way to get the buffs anyway. If you want to stick close to Dalaran, honestly EoA and VoTW aren't far away and the instances while longer, aren't that much longer. EoA is one of the easiest dungeons to deal with on pretty much any affixes.

I realize this is about AP farming, but I find Maw one of the more annoying instances in regards to affixes. Bolstering makes a lot of the pulls in there smaller, skittish is annoying regardless, and then you have a bunch of mobs that can't be snared or stunned, meaning necrotic and raging are far more difficult to deal with than most other dungeons. This is more about pushing higher keys, not so much AP, but it can be applied to other dungeons. CoS for instance, except on super high Tyrannical is barely affected by any affixes because all of the pulls are 3-4 mobs max, with the only annoying bolstering pack being one mana wyrm pack near the beginning, which can be dealt with really easily anyway.