Check out what people are saying about salt water it is not the best for your equipment. as for the finishes we have an above ground pool with deck built around it has 25 yr warranty and we are using chlorine and will stay with that it has served us well for the last 8 yrs with no problems.

What geographical area are you in? They are both good pools and costs vary from location to location.
You need unbiased information on which is best. The concrete builder will tell you their the best choice and the fiberglass builder may not give you the honest representation of his.
I have sold all three types of pools for 28 years.

We are in Southwestern Ontario, Canada. We are now looking at steel with concrete bottom vs fiberglass.

http://ths.gardenweb.com/forums/pools

Perhaps you would like to ask your question on the Houzz forum that deals with Pools

Fiberglass Pro: Finish doesnt need to be redone every some many years. Con: Shapes are limited to what manufacturer can make. Concrete Pro: Any size shape can be build. Con: Cost in midwest area is sometimes twice as much as fiberglass.