I play ACs for three things: my friends in the ACs, the gameplay itself, and the role play/plot. All three of these are fun, but my main problem is with gameplay. You see, as it stands, the two ACs I've participated in have been superhero types, where a die is rolled numbering from 1-20. The outcome determines the success or lack thereof in relation to your orders. This number is modified by mainly two things: feats and your 'stats'.
The 'beef' I have with this system is that it is, at it's base, glorified gambling. Yes, choices you made prior to the game's beginning determine the outcome, but the game itself is betting that you get a good roll, modifiers or no. Now, this is of course fun, but has many a time led to situations where a seminal moment has been decided by whether the RNG spit out a 1 or a 20. This leaves me, the player, who has invested hours of their time in this mission, feeling helpless and unimportant to the overarching game.
Additionally, the dice are often unreasonable or silly. In a recent AC mission, RedSpy, playing as an practiced illusionist failed to create a small snake in a no pressure situation. This is ridiculous, but not the least of the problems that spring up from the system. A notorious example, which I've heard much about (I wasn't around when it happened), was someone ordering to shoot at the sky, gambling that they'd get a low roll. Humorously, they did, and somehow missed the goddamn sky.
A third problem with this method of running an AC is that the game can turn into a meaningless firefight, with players spamming the same action until they get a high roll. Not only does this make the game boring, it summons the same problem mentioned earlier: players are left helpless, and the game loses import.
One redeeming factor is that this gambling allows for rich role playing, as people can say and do mostly whatever they want, with everything turning out fine as long as they score high rolls. This is a mixed bag, though, as their actions become secondary to the rolls. Of course, character relations is a big part of RPing, but I am mostly referring to other types. For example, one could say "whack someone with a fork, in order to knock them out." If they got a high roll, the fact that they just tried to knock someone out with a dinner fork doesn't matter. Instead, their 18/19/20 takes the forefront, and they knock the person out. Similarly, the same could be tried with a war hammer, and if they got a 3, they'd still miss. Of course, this can be altered by GM, but the underlying foundation leads to it.
Thinking about it, I believe the best solution would be a game more based on RP. Most actions would be judged to either succeed or fail by the GM, according to the plot, the player's powers, and the situation they're in. If it is a high pressure hostage negotiation, a character's persuasion magic may fizzle, but if someone is conjuring a sword to impress party guests, it would work consistently.
Obviously, this has major flaws. However, I would probably enjoy playing it more because my choices have more impact beyond wishing for a certain roll, and RP takes center stage over gambling. Much of an AC like this would come down to the GM, but it would be worth a try.
Thanks.