I think you question is how do you build the body rather than what material you use. I use Polar Fiber most of the time because I like the action it gives the fly. Some of the other materials seem to stiff to me.
These are high, flat flies tha mimic pinfish or menhaden (sorry, I know those are saltwater baitfish, but I don’t know the freshwater equivalent, but sort of like the high flat body like a bluegill). As for the technique, you tie is a series of small bunches that flow back over the top of each other. Start near the bend of the hook, tie a small bunch of material on the top of the hook (this is not exactly like your first sample, which are tied bendback style). Next tie a small bunch of the material, in a lighter color on the bottom of the hook. Then tie another small bunch of material on the top of the hook, flowing back over the top of first bunch but letting some of the fibers flow straight back to cover the thread of the first tie in. Then repeat this on the bottom of the hook. Keep repeating this alternating top to bottom, till you are almost to the eye. Tie off forming a small head. I use Goop to glue on the eyes.