I guess I thought I'd get this one out of the way first, because it's kind of obvious. God totally arranged everything, so if you don't thank Him, you're pretty much a heathen and committing all kinds of heresy as well as all kinds of suckage. But the problem with this one is that you sort of also have to "thank" him for the bad things, too, because he's sorrta responible for them, and that's kinda hard for me? "Thanks, God man, for the 110 dead in the India terrorist attacks" doesn't really sit too well. So God takes place #5.
4. Axl Rose
This one kind of has the opposite problem, where instead of having to thank someone for too much stuff (like with God), you only really have to thank Axl Rose for one thing, which is for Chinese Democracy not beeing too awful. Which, you know, you should probably thank him for. But to be honest, it's not one of your best options for thankable entities.
A pretty decent third way here is to invent a fairy-based religion with fairies that are slightly less powerful than God but more powerful than Axl Rose, so you can credit them with all of the good things but none of the bad things. They are not responsible for the bad things because they are locked in an eternal struggle with the Mugwumpian eyebrow demons who cause all things wrong with the world and what the Christ is wrong with me for writing this.
2. Your parents, for having you
This is a pretty good one. If you like life overall, and you're glad you were brought into the world, some good people to thank are the people who sexed each other to make you. All of your personal happiness is basically due to them, and if your personal happiness is any appreciable amount greater than your personal sadness, then they deserve some pretty big credit for making each other pregnant.
On the other hand, even though they made it possible, you are kind of the one who has experienced all your happiness, and figured out ways to funnel your sadness into a kind of sick happiness by doing things like making terrible ironic statements about God and terrorist attacks. Maybe that last one just applies to me, but I'm sure there are some other ones of you out there. Word up, brothers. Even if it doesn't apply to you, I think it is pretty good to thank yourself for everything you have done. For yourself. Good job, you! And good job, me! For thinking of doing this!