Glee has always been a "mixed bag" sort of show. Some episodes, and even some entire seasons, could be considered legitimately great television. Other episodes, and other entire seasons, are more widely mocked - even by the show's own fanbase.
The same goes for the performances. Some song choices and performances are genuinely fantastic and may even eclipse the originals. Other song choices and other performances are both misguided, misplaced, and veer on the annoying. Rachel is the de facto protagonist of Glee, and therefore, is given some of the most substantial musical material. And being the best singer, many of them are hits, but certainly not all of them.
Best: It's All Coming Back To Me Now
Even the fans who hate Rachel have to admit that she absolutely killed "It's All Coming Back to Me Now." The song is featured in Nationals, with Rachel performing it at the 2012 National Show Choir Championship.
She hopes that the song and performance will attract the attention of Carmen Tibideaux, the Dean of Vocal Performance and Song Interpretation at NYADA. Needless to say, the performance proved an incredible success, and even the typically cold and unimpressed Carmen was left smiling.
Worst: The Chipmunk Song
Season five's Previously Unaired Christmas has to be one of the weirdest episodes of Glee, and it features a truly bizarre performance of "The Chipmunk Song." The entire performance plays out like a fever dream, as Rachel and Santana inhale helium to make their voices higher (and thus sound like chipmunks).
They proceed to dance around Cody, acting as his elves, before collapsing in what seems to be a drunken stupor. It's amazing to think that Glee can oscillate between Broadway belters to...whatever the heck this is.
Best: Don't Rain On My Parade
Speaking of Broadway belters, it doesn't get much better than "Don't Rain On My Parade." In this episode, Rachel is able to embody her longtime idol, Barbra Streisand, by singing this tune, perhaps the most famous to come from Funny Girl. The performance can be found in Sectionals, as Rachel performs it at the 2009 Western Ohio Sectional Championships.
It takes a lot of talent to measure up with Streisand. Luckily, Lea Michele (and Rachel) has that talent, resulting in a magnificent performance of a magnificent song.
Worst: Let's Have A Kiki/Turkey Lurkey Time
Aside from maybe The Chipmunk Song, this could very well be the lowest point of Glee. Featured in the fourth season episode Thanksgiving, this is yet another bizarre fever dream that takes place within Rachel's apartment.
The "Let's Have a Kiki" segment is passable enough, but Rachel eventually breaks into "Turkey Lurkey Time," and viewers can only cringe in embarrassment. The connection to Thanksgiving is obvious, but just because they could do something doesn't mean that they should have.
Best: Cry
Kelly Clarkson's "Cry" features in the third season episode. "Choke." Rachel had a string of fantastic solos at the end of season three, and "Cry" is undoubtedly among them.
Upset over her blown NYADA audition, Rachel sings "Cry" to express her great disappointment, and it serves as the perfect cathartic release for a deeply emotional and upsetting episode. The theme of the song also carries over to Puck, who receives an F on his test while Rachel is singing the song in the auditorium.
Worst: Creep
Of all the bands to cover, Radiohead has to be one of the toughest. In season four's "Guilty Pleasures," both Brody and Rachel team up for a duet, performing Radiohead's iconic "Creep." It's a good song and a somewhat decent performance from the two.
However, "Creep" is very much engrained within Radiohead and Thom Yorke, and hearing Lea Michele sing the lyrics just doesn't have the same impact. It comes across as a corporatized, very sanitary, very safe version of an otherwise gritty and deeply raw tune.
Best: Defying Gravity
"Defying Gravity" has to be one of the greatest Broadway showtunes in history, and Lea Michele absolutely nails it in season one's "Wheels." Granted, the success of this performance isn't all down to Lea Michele, as Chris Colfer certainly holds his own.
In fact, the two remain neck in neck throughout the performance, and Rachel is deemed the winner only after Kurt intentionally throws his chance. It's arguably Colfer's greatest moment, and it's certainly one of Michele's best.
Worst: Poker Face
There's nothing inherently wrong with "Poker Face." How can someone go wrong with a Lea Michele, Idina Menzel duet? It's just a very weird performance, and it's greatly diminished by the song's meaning and the unique arrangement.
"Poker Face" isn't exactly a suitable song for a mother-daughter reunion, and the weird lounge/coffee shop arrangement of the song doesn't do Michele any favors - especially when it comes to the playful "oh oh ohs" of the pre-chorus. It was a risk, but one that didn't necessarily pay off.
Best: Jar Of Hearts
Featured in the episode "Prom Queen," Rachel sings "Jar of Hearts" to express her disappointment and broken heart towards Finn. It's a great song choice, as the lyrics perfectly convey Rachel's feelings of hurt and betrayal.
It's also perfectly sung and wonderfully performed by Lea Michele, with her side glances towards Finn speaking volumes about their current relationship status. It's moments like this that prove just how good Glee could be.
Worst: The Climb
Okay, so The Climb is intentionally bad, but the point of the matter is that it's by far Rachel's worst solo. The song is found in the first season episode "Laryngitis," the title of which comes from Rachel's encounter with tonsillitis.
Her fellow Glee members suspect that something is wrong after a terrible performance of Miley Cyrus's "The Climb," complete with horribly off pitch and off tune vocals. It's a hilariously bad performance, and it proves that even the greatest singers have their off days.