Some people are telling me to use organic shingles, and others are telling me fiber glass shingles. What's the difference and which do I use?

What you choose to use is up to you. Most roofers in the northern parts of the country prefer the organic shingles, while the southern parts prefer the fiber glass shingles. The fiber glass shingles are easier to work with and the organic shingles have more asphalt and are heavier and more expensive to manufacture.