The reason why we used GM for this jam game (and all other jam games so far) is that we're the most familiar with it compared to other engines and we know that we can create stuff fast in it because of that.
I hesitate to give advice on which engine you should learn, because I'm not super familiar with engines besides GameMaker and Unity. But I will say that if you want to make 3D games, GameMaker doesn't have great support for that, so you'll be better off learning Unity, Godot, Unreal or any other engine with proper 3D capabilities. If you do want to make 2D games, GameMaker is great!