re: Would anyone recommend a fiberglass pool over gunite pool if I don’t want a custom shape?

I would just go with a smaller nice gunite pool (12-18k gallon). If you keep the water balanced properly, mainly keeping pH and total chlorine in check...your gunite will last a very long time. We have a 15k gunite pool with spa overflow. It's the perfect size for our family and is relatively easy to maintain due to size.