You're doing OK with the little experience you have. They'll all catch some fish. I don't know what to say about the senko type fly, except let us know how it does for you. Senko style plastic baits have a particular action as they fall, and I'm not so sure it can be duplicated with yarn. That does not however mean that fly won't catch some fish.
IMO, the crayfish could have used a different hackle, something more brown or olive & with shorter fibers or no hackle at all. Tie the hackle in by the tip & wrap forward & you'll get a nice taper to it. Works well when tying buggers too.
That style is similar to some of the "Bonefish" or "Flats" types of flies, which I like to use as crayfish patterns, and I don't add a hackle to the body. Don't clip the hackle, the fibers provide movement, especially at rest, which is not something you want to remove from a crayfish fly. I do like that variegated chenille body, that's a good color combination!
I'm a fan of pink buggers too for Crappies, and olive as well for many species. The only critique I can make is I feel the olive bugger could have used a bit more marabou in the tail.
Looks like you may be using marabou from a turkey flat, where you have to remove the fibers from the sides of the feather. They're OK, but blood quill marabou IMO, makes a nicer looking tail on a bugger. I tie some big buggers so will put 2 blood quill feathers together for the tails on my buggers. On smaller sizes a single feather is fine. However, use what you have for now, as the fish won't likely care either way. Just something to keep in mind when you need more marabou.
Here's some buggers I tied recently. These are all size 1, tied on worm hooks. The tails are tied with blood quill marabou & the hackle is tied in by the tip & wrapped towards the eye. I also like to use some of the fluff at the base of the hackle when wrapping buggers.
Slightly different versions!