For HS this is a bit different than I would say for HS. Not sure what you're situation is, but I consider these to be some of the more challenging 1s.

Some newer ones:

Me (Reaffirmation)
Rust Belt (Owens)
A Scottish Festival (Balmages)
Lost Woods Fantasy

Older:
Mythos - Bernotas
An Irish Air - Sheldon
The Band in the Square (on the Fourth of July)
The Piper and the Captain (Interesting piece because you can do just two movements, I've worked on this with a NV HS group before)