The reason that I do not believe in evolution is primarily because of how extremely complex humans are. If we are this complex, why isn't there one other species out there that comes very close to our intelligence and complexity. I don't believe chimps and apes are even close to as smart as we humans are. I believe something was involved in making as complex as we are.
Ah, 'Irreducible Complexity'. My favorite logical falacy.
Humans really are no more complex than any other animal. Our brain is the same basic organ as many other mammals, just bigger (besides, other animals are smarter than others, we just happen to be on top for this trait). This isn't always an advantage as a bigger brain means more resources needed by it. And other animals have better, and more complex, systems than us. Squids have a very complex skin system that alows for both color change and bioluminescence. The stomach system of a cow is far more complex than ours, a birds lung system is more complex. Other animals have better sight, better smell, better reflexes, ect. We have intelligence, but it doesn't really make us any more complex than another animal.
And evolution is how we all got so complex in the first place. You add trait upon trait, billions of traits for millions of years, and things can get very complex. Well, some organisms remain simplistic because they remain well-adapted. Others need to get more complex.
As well, no animal is completly perfectly adapted. Humans for example: Our eyes have a bundle of nerves in front of a receptor that cause a blind spot, by walking upright we have more pressure on our back and necks which causes serious problems. The human hip is the worst, for the possitioning it upright makes child-birth more painfull and dangerous.
All in all, things being complex only goes to support evolution, and not disprove it.