You made me laugh because I was thinking exactly the same thing last night when Blake sang for Sundance's study tape.
Billy and Aaron are frustrating opposites for me--it's like Billy does all songs well but none of them keepers, whereas Aaron does most songs badly but has a few real gems (YMMV). Frustrating. I tend to think Billy needs to stop singing to The Audience and sing to someone. Aaron needs to stop being on the show, but more because I think it is just not the right venue for what he does best.
I liked Wé's song, but I always feel like she's having to outsing all the production, which detracts from the overall thing.
This is probably just me, but it drives me batty when performers with guitars abruptly stop playing the guitar mid-song and more so when they do this for long periods of time, Josh.
Lastly, what are those little earpiece thingies they wear? I noticed Billy took one of his out in the middle of his duet with Christian. Does it affect how they perceive pitch? Because aside from the nerves and the lives aspect, a lot of these guys sound horridly pitchy on stage to the point where it's just weird. They don't sound like that on the iTunes snippets or in rehearsal.