Oh man!
I honestly have to say that I think I loved all of her Dearest performances, from the era when that was her single. She was always vocally on point, and has not had vocals anywhere near as CD-perfect and strong as that since. The two posted were absolutely fantastic, but I've also always loved this one:
http://www.youtube.com/watch?v=y4PSUO2Jr7M
I would also add to the list M (unplugged) from Stadium Tour (I think?). Teddy Bear from AT04 (I think that was the year) was also heart-wrenchingly great.