My first go-to is a size 16 Sparkle Pheasant Tail, as shown at:
I also always have zebra midges in black/silver, black/red, and olive/gold in size 18 and 20, brassies in size 22, Copper Johns and Hare's Ears in 14 and 16, and a simple peacock herl/gold wire ribbed midge in 18.
For dries I always have size 14 Stimulators, size 14 and 16 Elk Hair Caddis, size 14 and 16 Parachute Adams, and size 14 and 16 Parachute Hare's Ears. Also a hopper or two and a couple of foam beetles.
I rarely fish streamers, but I always carry a couple of size 8 and 10 olive wooly buggers, and a white Zuddler.
If I'm going near warm water or salt water, I've got chartreuse/white and olive/white clousers in 4 - 1/0, a couple crease flies, a couple Gurglers, and a handful of wooly buggers.