Hermione Granger It's hard to picture Harry and Ron surviving without Hermione Granger, the brightest witch of her time.
If you just went off of marks, Hermione would win, as she is good at most things while Snape truly excels at Defense and Potions. If you just went off of one of those two, Snape would win as he goes above and beyond in them.
While Hermione was intellectual in the traditional sense of the word, Luna's smarts were more in being creative and artistic. She was able to do things like constructing a lion's head that actually roared, and she also clearly was able to see the world in many different dimensions with a great imagination.
Tom Riddle/Voldemort
Professor Dumbledore once said that Tom Riddle, a.k.a. Lord Voldemort, a.k.a. "He Who Must Not Be Named" (Ralph Fiennes/Hero Fiennes Tiffin/Christian Coulson), was the most brilliant student that Hogwarts has ever known.
It shouldn't be hard to believe, but Draco Malfoy was the second most intelligent student in all of Harry's year. That Slytherin determination can accomplish quite a lot. Draco received at least three OWLs (including both Transfiguration and Potions) and he is very competitive with Hermione.
Albus Percival Wulfric Brian Dumbledore was the only wizard Voldemort ever feared and the only one who could have defeated him in a duel. Albus Dumbledore is the most powerful wizard in the Harry Potter.
She is also the first one of her age to be able to cast non-verbal spells. Hermione is a competent duellist – Rowling has stated that during the first three books Hermione could have beaten Harry in any magical duel, but by the fourth book Harry had become so good at DADA that he would have defeated Hermione.
Later in the year, McGonagall duelled with Death Eater Alecto Carrow during the Battle in the Astronomy Tower and later learned of Snape's murder of Dumbledore. McGonagall was initially appointed as Headmistress, but was demoted after Voldemort took control of the school and placed Snape as Headmaster.
A Professor at Hogwarts School of Witchcraft and Wizardry, Snape is hostile to Harry due to his resemblance to his father James Potter, who bullied Snape during their time together at Hogwarts. As the series progresses, Snape's character becomes more layered and enigmatic.
Harry's other best friend, the bookish and kind Hermione Granger can't be beaten in the classroom. Harry recognizes her as his year's best student and even said so at some point. But while Hermione can ace any test, she can't quite keep up with Harry on the battlefield.
Catelyn DID swear an oath to Walder. But, then, it's pretty dramatic to go and have the woman (and her family) slaughtered. Family drama aside, DAMN. This means ARGUS FILCH KILLED HERMIONE'S MOM!
Dumbledore may have been a legendary wizard, but he can't be compared to, well, Merlin, a wizard so legendary even Muggles know of his exploits. Merlin was the world's most famous wizard, and, arguably, the world's most powerful.
DRACO MALFOY
Harry and Draco were pretty much neck-and-neck when it comes to dueling and wand-related stuff. It was only until Harry got a hold of Snape's diary and channeled his Slytherin tendencies that he was able to win against Malfoy. As a result, he nearly killed Malfoy in The Half-Blood Prince.
Avada Kedavra
Topping the list for the most powerful spells in the Harry Potter universe is no other than Avada Kedavra, Voldemort's favorite to instill his will and fear onto others. The spell itself is a play on Abra Kadabra and is easy to cast by just about anyone in the Wizarding World.
She was fully capable of disintegrating Snape's fiery serpent he sent at her with just a wave of her wand and instantly turning it into swarm of daggers without saying the incantation. They were so powerful even without the incantation that he was forced to hide behind a suit of armour.
Godric Gryffindor, the founder of Gryffindor house, was one of the most powerful wizards of his age, so powerful that he was said to be the greatest duelist of that era. Always ready for battle, Godric wouldn't just use a simple wand, he'd also wield a mighty sword.
Of the characters in the books, the top-tier wizards are pretty clearly shown to be Dumbledore, Voldemort, and Grindelwald. If one accepts that magic has advanced since ancient times, these three are probably even greater than the Hogwarts Founders themselves.
At the ball, Harry and Parvati are seated at the head table with the other champions, including Cedric and Cho, as well as Krum and a beautiful girl who turns out to be Hermione. Ron, who has annoyed his date by staring glumly at Hermione all night, accuses Hermione of fraternizing with the enemy.
Hedwig's killer is not explicitly identified, so he/she may have appeared in other books, films or video games, but the only known appearance is Harry Potter and the Deathly Hallows and Harry Potter and the Deathly Hallows: Part 1. A popular fan theory based on book canon suggests that Snape may have killed Hedwig.
Her real parents were Daneel and Dean Novak, Pureblooded wizards. Turns out Daneel was Tom Riddles younger sister, Daneel Riddle. Of course, the Riddles were related to Salzar Slytherin himself, and this made Hermione the living heir of Slytherin. The problem with being a female Slytherin heir, is that they're cursed.
Verdict: Snape Is the Stronger Wizard
McGonagall is surprisingly skilled in the Dark Arts but not on the same level as Snape. She's also most likely incapable of casting the Killing Curse, which puts her at a disadvantage.
Not to be blunt, but without Hermione, Harry and Ron would have died many times over. As would loads of other people. For all the times Ron and Harry took the mick out of Hermione, you can bet a few Galleons they wouldn't have made it through seven books without her.