Multiple Hair Issues - Which is the Best Shampoo to Use?

I used to have straight, shiny, medium fullness and full of bounce hair. Now that I'm in my late 40's, my hair has changed to dry, frizzy, fine (thinning), not much shine, no bounce and graying.

What is the best shampoo/conditioner I can use to address all these problems? Especially in hot, humid weather, it doesn't matter what product I use for frizzy hair or even if I use a flat iron - nothing seems to get rid of the frizz - never had this problem before.