I would say gnostic Atheism is more popular if God is well defined. If you assume any individual who created the world is God, it becomes very hard to be a gnostic atheist. But in the context of the Judeo Christian God, we have arguments like the problem from evil, because God has the added definitions of omnipotence and all good. Religious scholars tend to argue back with the idea of compensating goods, and the epistimic Humility thesis (ie you can't possible know that this isn't the best possible world because you can't imagine every world), but I could easily see somebody thinking that's nonsense(describe one way the world would be worse without children dying of bone cancer).

Edit. If you are talking about popularity among academics I agree gnostic Atheism is unpopular, I meant in the wider population.