Hi
For me the best nymphs for grayling or just plain hares ears, PTN's and black nymphs. It is more important to get the fly to the right level then to worry about the pattern to much.
The best patterns for me are also normally tied on jig hooks so as not to catch the bottom and are heavier because of the slotted bead over the drilled bead.
the best advice i can give you is use what you have confidence in and make sure you get them on the bottom!
If you want to experiment in flies however, the best ones are Flash back caddis, and the Sisak Jig. Or any of the flies at
Unique Flies: Welcome.
James