Bästa

tl; dr: 5 gånger

Harry nämner på flera platser att det här är "den bästa dagen", jag kommer att skissera följande exempel. Tänk på att "det bästa någonsin" är ett vanligt begrepp som ungdomar använder när de känner sig upphetsade (detsamma gäller det motsatta "värsta någonsin"); vi gillar att överdriva.

Harry Potter och The Philosopher Stone
Dursleys och Harry besöker Zoo i Surrey för att fira Dudleys 11 th födelsedag. Harry tycktes njuta av besöket på Zoo och kände att det var en av de bästa dagarna som han hade haft på ett tag:

[the lemon ice pop] wasn’t bad, either, Harry thought, licking it as they watched a gorilla scratching its head who looked remarkably like Dudley, except that it wasn’t blond.
Harry had the best morning he’d had in a long time. He was careful to walk a little way apart from the Dursleys so that Dudley and Piers, who were starting to get bored with the animals by lunchtime, wouldn’t fall back on their favorite hobby of hitting him...
-Harry Potter and The Philosopher's Stone, Chapter Two (The Vanishing Glass).

Harry Potter och The Philosopher Stone
Harry finner ut att han är en trollkarl på sin 11 th födelsedag. Han känner att han har den bästa födelsedagen någonsin:

“You all right, Harry? Yer very quiet,” said Hagrid.
Harry wasn’t sure he could explain. He’d just had the best birthday of his life — and yet — he chewed his hamburger, trying to find the words. ...
-Harry Potter and The Philosopher's Stone, Chapter Five (Diagon Alley).

Harry Potter och The Philosopher Stone
Harrys första Hogwarts Christmas, och det visade sig vara hans bästa jul hittills:

It had been Harry’s best Christmas day ever. ...
-Harry Potter and The Philosopher's Stone, Chapter Twelve (the Mirror of Erised).

Harry Potter och The Philosopher Stone
Harrys första slutet av årets fest. Efter att ha besegrat Quirrelmort, deltar Harry i slutet av årsfesten där prof Dumbledore tillkännager Gryffindor som Cup-vinnarna:

It seemed as though life would be back to normal next year, or as normal as it ever was at Hogwarts.
It was the best evening of Harry’s life, better than winning at Quidditch, or Christmas, or knocking out mountain trolls . . . he would never, ever forget tonight. ...
-Harry Potter and The Philosopher's Stone, Chapter Seventeen (The Man with Two Faces).

Harry Potter och Azkabans prizoner
Harry och hans lag övar för sin match mot Ravenclaw den månaden och under en av metoderna säger Harry att det var den bästa Quidditch-träningen någonsin:

It was the best practice ever; the team, inspired by the presence of the Firebolt in their midst, performed their best moves faultlessly ...
-Harry Potter and The Prisoner of Azkaban, Chapter Thirteen (Gryffindor versus Ravenclaw).

Värsta

tl; dr: 4 gånger

Harry Potter och The Philosopher Stone

It was lucky that Harry had tea with Hagrid to look forward to, because the Potions lesson turned out to be the worst thing that had happened to him so far.
-Harry Potter and the Philosopher's Stone, Chapter Eight (The Potions Master).

Harry Potter och Secrets Chamber
Funnily nog kallas det första kapitlet "Den värsta födelsedagen"; men det finns inget omnämnande av Harry om det värsta av någonting.

Harry Potter och Secrets Chamber
När Ginny blev bortförd av monsteret i hemlighetskammaren:

“The Heir of Slytherin,” said Professor McGonagall, who was very white, “left another message. Right underneath the first one.
‘Her skeleton will lie in the Chamber forever.’ ”
Professor Flitwick burst into tears.
“Who is it?” said Madam Hooch, who had sunk, weak-kneed, into a chair. “Which student?”
“Ginny Weasley,” said Professor McGonagall.
Harry felt Ron slide silently down onto the wardrobe floor beside him.
“We shall have to send all the students home tomorrow,” said Professor McGonagall. “This is the end of Hogwarts. Dumbledore always said . . .”
...
It was probably the worst day of Harry’s entire life. He, Ron, Fred, and George sat together in a corner of the Gryffindor common room, unable to say anything to each other. Percy wasn’t there. He had gone to send an owl to Mr. and Mrs. Weasley, then shut himself up in his dormitory.
-Harry Potter and the Chamber of Secrets, Chapter Sixteen (The Chamber of Secrets).

Harry Potter och Fire of Fire
När Ron slutade prata med honom för att alla trodde att han hade satt sitt namn IN FYAH'S GOBLET!

The next few days were some of Harry’s worst at Hogwarts. The closest he had ever come to feeling like this had been during those months, in his second year, when a large part of the school had suspected him of attacking his fellow students. But Ron had been on his side then. He thought he could have coped with the rest of the school’s behavior if he could just have had Ron back as a friend, but he wasn’t going to try and persuade Ron to talk to him if Ron didn’t want to. Nevertheless, it was lonely with dislike pouring in on him from all sides.
-Harry Potter and the Goblet of Fire, Chapter Sixteen (The Chamber of Secrets).