My favorite is what ever is catching fish. I've been spoiled enough here in British Columbia that if they aren't biting dries on top then I usually don't bother. Nymphs are less fun to fish. I fish lakes, rarely any kind of stream. The "teawater" lakes full of bugs and moosey shore lines are fly fish heaven. The larger, crystal clear lakes sometimes work for flies but I usually do better fishing small salt water salmon jigs near the bottom with spinning gear in that kind of water.<P>To choose one fly I'd go with the Muddler Minnow. I fish it dry and I'm sure the fish think it is a grasshopper. Last summer on a lake in Alberta when the wind was blowing grasshoppers onto the water, I kept catching fish and gradually chewing up or losing flies for one reason or another until all I had left that looked like a grass hopper was a huge Muddler the size of a mouse tied on a 1/0 or 2/0 hook. Those big rainbows just clobbered it. <P>In Central BC for many years the Black Doc Spratly was the most popular fly for lakes. In mid to late summer, just after sundown on those central BC lakes, a BIG fly of almost any kind as long as it has a white white upper wing or white streamer on the top, is just deadly on really big rainbows. I don't have clue what they think it is. The best version I've used was a hair winged California Coachman, in a number 2 long shank hook.<P>For cutthroat, a friend tied at my request some Muddlers with an orange body. His name is Birchhill and we called it the Birchhill Muddler, or more correctly I was told, the Birchhilll Minnow. Cutthroats like orange.<P>I'd like to try bluegill on a fly sometime.