If you had enough evidence to know that God is real, would you love Him or hate Him or what?

[Final-Fan]

First off, I would like to thank the OP for his own honesty about his likely reaction to (hypothetical) 100% proof that his belief in God is wrong.  Of all the atheist answers so far, I think "go into denial" hasn't been one of them—explicitly, anyway!  Maybe a few are masking it. 

I think I will have to give more than one answer to your own question. 

1.  First I will assume you mean "the God of the Bible".  But even this is an interesting case because it seems to me that the way he acts has changed significantly from OT times to NT times to today.  Does he act in different ways to us based on our cultural development to try to spur us on in different ways?  If we advance further from where we are today will he act differently towards us in yet a new way?  What is really happening to those who die?  (Different Christians believe different things:  Purgatory for example.)  If the Bible is completely true then I would have to take another look at it to see if a God that did those things, and then changed how they act towards us, was one I should revere.  Having some insight into their motivations would help. 

To me the Book of Job, in particular, is really inexcusable.  I can't see how anything could justify such a petty act.  I have a post on this subject here.  Now, of course this could be countered with "all part of the Plan" but I don't know how I could just blindly assume that was true.  Despite all that, though, it might be forgivable depending on all the rest of it—but to be clear, if I didn't have specific knowledge of an excellent reason to let this happen it would be me forgiving God for his past misdeeds. 

Faced with the prospect of Hell, I think I would go with "Twilight Zone" style false worship if that would be enough to qualify me for Heaven.  Like JWeinCom, I am not so proud that I would refuse to bow to save my life.  However, if I would have to do horrible things in his name in order to get the reward it would be a different story. 

2.  If the question is limited to exactly what you said, "a supreme, eternal, almighty being had created you and the Universe, and was the very thing that sustained everything," then I would certainly be grateful for my existence, but how grateful I was would depend on what "sustain everything" means. 
2a.  If God is simply "keeping the lights on" and doesn't have any specific control over events, then the bad things that happen aren't God's fault and we should be grateful for what we are given even if it's an imperfect gift.  (However, I'm not sure if my feelings would rise to "love and worship" or just be deep admiration and gratitude.  A favor we could probably never repay, but not one that really influences day to day life or that I think about on a daily basis.  Send them Christmas cards and so on.  If we are asked to do something, do it.) 
2b.  But if God has absolute control over the universe (with the exception of our own free will) and still throws hurricanes and asteroids and smallpox at us, well—why should I love such an abusive parent?  Sure, we wouldn't exist without them, but that doesn't mean it's okay to smack us around.  I'd recognize what God did for us but still resent them.