Two Killer Patterns
Here are two fly patterns I always carry with me. Over the years they have consistently produced fish in every location I've used them. I'll fish them as nymphs, emergers, or streamers depending on conditions and inclination.

Improved Western Coachman:
Component
Material
Comment
Hook TMC 3761 ~ any heavy wet fly hook  
Thread 6/0 danvil black or olive  
Rib None  
Body reinforced peacock herl use thread or a piece of metallic green thread ~ latter preferred
Tail golden pheasant (traditional) or brown antron  
Wing x-lon grey or cream generally like the kinky over the straight z-lon ~ some tied with a few strands of white ice dubbing mixed in.
Legs Brown or grizzly hen hackle tie-in by the tip with 2 wqraps ! on small flies I'll strip the fibers off one side
Head couple turns of bright green dubbing  
Antennae root beer micro krystal flash  

Swimming Prince:
Component
Material
Comment
Hook TMC 200R my favorite hook
Thread 6/0 danville black or olive  
Body reinforced peacock herl same as improved Western Coachman
Tail brown filoplume  
Wing x-lon grey or cream with flat white rubber wings on top that extend to the back of the hook as an alternative to rubber use mirage flashabou ~ opal/ice blue
Legs brown or grizzly hen hackle tie-in by tip
Eyes none  
Head tungsten bead ~ gold, black or nickel can use a regular bead ~ use a little dubbing behind the head to push the legs back and act as a thorax.