Fiberglass rods have a few things going for them cheaper /very sturdy /cast ok.
Carbon rods are generally lighter and if you put in the same effort in casting them they will enable you to cast further .
down side is they can be a bit more fragile and don’t like being knocked about on rocks etc.
Have a look at http://www.kilwell.co.nz/Saltwater_Rods … Craft.html
for a overview on the kilwell range they all work quite well.