1st: Echoes of the First Lillend. Very fluffy, very cool. A bit low-impact, though - Like a lot of magical locations tend to be more trouble than they're worth, and this is no real exception. To sum up: Cool concept, mechanically low-impact.

2nd: Devilish Musician. Once again, I like the flavor. My mechanical problems are mostly in the editing camp, with some sloppy wording (How many times per day can he bargain? Why does he have save penalties vs morale effects, when every 3.5 morale effect is beneficial?)

3rd: Cadence Casting. It's undeniably a cool concept, but I think it grew a bit too big for its britches. This is something that should be expanded into its own class, not stuck into the bard, it's just too much of a hack. Having to learn a bunch of sub-par spells... The chords being "spells" that are cast as a free action without being known... It just doesn't really fit inside of the system where it's placed. Also, I'm sure 16th level spells break some things. A cool concept, and the implementation did the best it could given the framework, but I think the framework was wrong.

Most Original: Echoes of the first Lillend. It's really cool.

Most likely to use: Devilish Musician. I like Echoes a lot, but honestly by the time PCs are planeswalking around I probably don't want to spend a whole session making them perform for 24 straight hours for a 4k-equivalent reward. Musician has some pieces I'm not wild about but it's a solid concept, especially as an NPC-based plot hook or challenge.

best use of theme: This is tough. I love Devil went down to Georgia, and Cadence Casting is a cool design for spell chains. Since I feel like "best use" refers at least in part to my favorite design rather than my favorite implementation, I'm going to go with Cadence casting.