Good question. As far as the angels go, one would first have to assume that the Genesis account really happened. That is a big assumtion for me. But assuming you accept Genesis, you probably accept the rest of the Bible also. In that case you should believe in the God of love, justice, wisdom and power. These qualities would keep him from being corrupt. Again for me, it is hard to believe the Bible that has an almighty God who was involved in the every day details from creation to the death of his son, and beyond. Then, all of the sudden he is gone, uninterested, not concerned for thousands of years of human history. Why the change? Why now, when he sees injustice, wrongdoing going on does he not step in and correct matters like he did before? God doesn't change? If you believe the God of the Bible, he has changed drastically from the old testiment.
So I guess my answer is; what you believe about the Bible and the God described in it determines what type of personality God has. Maybe he was corrupt from the start by demanding exclusive devotion? I don't much believe in a God anymore, so my views will vary greatly from yours.
Just my point of view, I am not pushing it on others and I am not putting down anyone else's beliefs. My advice to you would be to read, research, then form your own opinion if you feel comfortable with it. If you don't feel comfortable with your conclusions, read and research some more. It can be a long journey, I wish you well on it.