THE BEST

Adam Lambert - Please Come Home For Christmas  2019 - a funny introduction (warning! there is an F-bomb dropped with much gusto), plus the emotions, wailing high notes, and vocal perfection* that we always expect from Adam, delivered with plenty of green glitter.  (*there may actually have been a note or two that were a tiny bit flat at the end, but easily forgivable for everything else he gives to this performance) https://youtu.be/iXk5SXP8tAQ?t=181

Usher - Have Yourself a Merry Little Christmas 2009 - flawless pitch, nice use of dynamics, adding some nice style with riffs but not overdoing it.  Only problem is the song is just too easy for him, there’s only so much he can do with it.  https://youtu.be/mCRCvQBrumo

Mariah Carey - All I Want For Christmas 1996 - The song that everyone wants to be able to sing, but few can really pull off.  Here’s the OG herself, rocking this performance. https://youtu.be/mTVJB--utdc

The WORST

Mariah Carey - All I Want For Christmas 2015 - Oh yes, I did it.  I put her on the best AND the worst lists.  Even Mariah can have a bad singing day, as showcased in this bombed performance.   It sounds like she had nodes or at least a case of laryngitis on this day.  In any case, it goes to show we are all mortals.  This video is a few moments with the vocals isolated, the whole performance can also be dug up.   https://youtu.be/OKIY9tCaqU0

Taylor Swift - Silent Night 2007 - What I do love is the glittery guitar!  Unfortunately, there is a lot to NOT love - the melodic arrangement makes the song almost unrecognizable, she is either singing super breathy or with a painfully pinched nasal belt, she has not discovered the use of her very nice chest voice yet, and there are some definite pitch issues.  But this video is a testament to how far Taylor Swift has come as a singer, the years of training have paid off! https://youtu.be/8upPX6pVNvk

Chris Brown - This Christmas 2015 - This really isn’t a terrible performance, but it’s on the weak side.  Scrolling through the comments, it became apparent that Chris was sick at this performance, and to be frank he kind of looked it, he is doubled over like he is about to puke for the majority of the performance.  He also stumbles around the stage and is quick to point the mic away from his mouth for the high notes, and sometimes just doesn’t attempt them at all.  Being sick is a legitimate excuse to have an off night, and I agree with the commenters who gave him credit for showing up and doing as well as he did considering he was under the weather.  https://youtu.be/ShedocL9nwI?t=106