Least wise for me, I hike very far in neoprene and I end up sweaty and damp. I'm much more comfortable when I'm dry.
5mm when wet, gains some weight, I don't enjoy packin around any more than I have to.
Was wearing breathables and develped a pin hole leak. Temp in the low teens. Was weaing wool socks and a heavier long underwear under the waders. Froze and broke the water pump impeller on my outboard, had to walk/wade my boat back to the launch along the shore, about 2 mi. Used my elect trolling motor in spots impassable. Never felt cold. Even though one leg was heavier than the other, they probably didn't weigh much more than 5mm.
Pin holes are easy to find, rubbing alcohol in a spray bottle, turn waders inside out, spray around the area where leak suspected and the pinhole will turn a dark color. Aquaseal to patch and you are good to go.