I love them both. Shes very good, but i like "Lost" better because she showed more range and versatilty, also using falcetto and belting.
On the BeeGees song, she didnt do the high part, but rather chose to lower it an octave to sing it easier, and i waited to at least hear her belt it high on the last chorus, but she still didnt, although it was still very good.
So, my choice is "Lost"
My handle there is DartStuff
I left my Drag0n handle in the comment as reference.