Depends on the specifics of your project...
Both do 2d, though PQ is specifically built for it, especially frame by frame animation. It also has better support for pixel art. Adventure creator is made for 3d too, so it's more fiddly to use for simpler 2d games.
Adventure creator uses visual programming, which is good for some but not for others. The main reason I started making PowerQuest after trying adventure creator was the I preferred a simpler text scripting interface than visual programming.
Adventure Creator has a bigger community and better support too. This forum is pretty dead as you've probably seen, though our discord is quite active, so if you ask there you might get more info from people who've used both.