I started out float tubing with Seal Dries! I could only fish occasionally, so whenever I could get out, I did. That sometimes meant some pretty cold water and windy days. You don't move around much in a float tube so you learn to wear expedition undies if you want to stay warm under those conditions.
Waders evolved. Neoprenes were a blessing. Not only were they warm, ,they flexed and stretched. All was well until I took up stream fishing. Mountain streams stay cold well into the summer. I found there were days that, even with 2mm chest highs, I was wishing I had left them at home and wet waded. And you look pretty silly walking around in (even lightweight) long johns, which you must
wear under neo's to wick away the persperation, and carring your waders.
100 degree air temp and 55 degree water is a hard combo to work with.
I put off going to breathables until they evolved to the point that they would not tear whenever you walked through the brambles..... And now I'll never go back to neoprenes. Even though I now live in the PNW and my river stays cold all year long. You can wear these things over anything from fleece to Levi's, dress pants, walking shorts. You can wear them all day long. Hike in them. Drive in them even.
You can always pack on more fleece and stay warm. But you can't work in cold water, warm weather and stay cool,,,,without breathables.
So,,,unless you sit in a boat all day in frigid weather, there is no question about it. Breathable waders, and a breathable rain coat. Two of the best investmates you can make.