Hi and welcome to the forum. Like you i was set on a fiberglass pool at the start. One of the most important parts of a fiberglass pool is the install, must be done right or it will crack if not installed level. Plus you will want a good back fill and that's not sand. So your installer/Pool Builder is the big choice you will make. You may only have a few to chose from. Next make sure the pool has a good gel coat. A good gel coat will not crack or fade in five years. On the plus side is that fiberglass pools can install quicker, algae has a harder time sticking to it and they say you can use less chemicals in a fiberglass pool. On the down side is you have fewer shapes to pick from(there are many popular shapes) the gel coat will eventually give out(12, 15 or more years for a good one and not 5 to 7 years as some cheap ones do) not as easy to add a spa or waterfall to a fiberglass pool. Hope this helps.
By the way, the reason i didn't go with a fiberglass pool is the only fiberglass PB in my area that i would have trusted never returned my 3 phone calls nor my two internet request.