Most here have already covered what I was going to say, but I'll put in my $.02 anyway.
1)What are some primary reasons for your lack of belief?
For me, Atheism is a default position. I've always been one, even though as a very young child I did possess what Gordon Allport would call an 'extrinsic' faith; that is, I was only Christian because my parents were. As I grew older I realized that I had never believed at all. The Bible stories I learned in my grandmother's strict Independent Babtist church never made sense. Even my mother's more liberal Babtist church teachings posed problems for me. I can now imagine my slight 6-year-old self adorning an oddly puzzled look when my Sunday school teacher got around to telling us about Noah's ark and Jonah being swallowed by the whale.
In hindsight, I also notice differences between myself and my younger sister. She's the type that used to say anything was possible, and that "humans could even fly" with God's help; I was always the one who told her that humans could never fly on their own - it was impossible. At the time, I was confusing myself because my parent's teachings told me that yes, humans could do anything with God's help. But my reason was telling me just the opposite.
Before anyone makes assumptions, my Atheism is not the typical 16 year old rebellion against my parents. In fact, I try to refrain from discussing my Atheism with my parents. My mom calls me a disgrace.
Oddly enough, I love being an Atheist. It seems to be such an intellectually honest position. My stance is that I will continue disbelieving until a valid reason
to believe comes along. I've never seen a reason yet.
2)Does the academic nature of science & evolution play a role?
I'm not quite sure what you mean here. I'm a scientifically-motivated person, so science is a central part of my life and way of thinking. So far science has proved to be the best method for discovery on earth. It's as simple as that.
3)What are some other factors that lead to your conclusions?
There are plenty. I've never seen, heard, or had any reason to believe that any other world besides the natural one exists. So why should I believe?
4)And what is your favorite god in the system of gods/mythology to use as an example?
Classical mythology is the most interesting to me. There are so many gods that anyone can relate to at least one of them.
Anyway, you might get better results if you placed this thread in the General Apologetics forum.