I'll give it a shot. I prefer straight eyed hooks. I use them for all my flies. Drys, nymphs, soft hackles, streamers, woolly buggers, bait fish patterns, poppers, sliders etc. Down eyed hooks can be used for all of the same patterns. My theory on that is that they are "traditional" going back to the days when flies were snelled. Upturned eyes I associate with salmon fly hooks, not sure why they were developed with the up turned eye, but they can be used for dries, wet flies and streamers. Hope this helps a bit.