Than the United States Congress? They're absolutely more effective. Congress may have been an innovative design in 1787, but it's grown into such a pile of misaligned incentives that it's almost completely dysfunctional.

As for corruption, I suspect agencies may be more or less corrupt on an individual basis. I don't have any hard data, but I suspect they're less corrupt on average. The Supreme Court has, repeatedly, given Congress members the go-ahead to be almost as corrupt as they want, while they're harsher on executive branch agencies.