These are my favorite flies (not in any particular order)

1. Caddis Pupa
2. Deep/Sparkle Pupa
3. Quill Bodied Olive Dun
4. BH BWO Emerger
5. Poxyback BWO Nymph
6. Elk Hair Caddis
7. Flash a Bugger (Olive/Black)
8. Rusty Spinner (CDC or Antron)
9. St. Vrain Caddis (esp. yellow)
10. BH F/B Pheasant Tail
11. UFO White body Black head (Miracle Midge is similar)
12. Brown Mono Midge
13. Biot Midge (Dry)
14. Sparkle RS2
15. CDC BWO Floating Emerger
16. Direct Hackle BWO (esp. for the smaller sizes)
17. Egg ala Muck
18. Grey Quill (an Adams will do, but in the larger sizes I prefer the Grey Quill)
19. S Sulpher Dun
20. WD40
21. BH F/B Pheasant Tail

Thats it for now. Now you must understand my views are colored by the water I fish and also by the fact that I hate to nymph. The rivers I fish the most often are (usually 8-10 times each per year):
1. Upper Colorado River (early summer till fall)
2. Cache La Poudre (before and after run off, actually the end of run off was great this year)
3. S. Platte (esp. Cheesman), usually in the late fall and early spring
4. Big Thompson (only spring and fall).

You may notice a pattern here. Some waters are too crowded in the summer, so I almost never fish them. Hell, they may not even be crowded, but I always think they'll be.
Specifically, the Big T. and the S. Platte.

Other rivers I fish 2-4 times a year.

1. San Juan
2. Frying Pan
3. Arkansas
4. Blue
5. Eagle