Pym already knocked Cho to 8th. And Banner said he's now 10th.

Is this the where the OP got the idea in the first place that Mr. Cho is the 7th smartest? Doesn't sound too official from that comic book reference. Maybe he's just a little full of himself.

In no particular order
Reed Richard
Victor Von Doom
Tony Stark
Bruce Banner
Peter Parker
Hank Pym

Honorable mentions
The Leader
M.O.D.O.K
Norman Osborn
Egghead

Amadeus Cho doesn't even crack my top ten

I'm inclined to go with this and dump Hank Pym. And I think I'd put Banner at the six spot. I'd also drop Tony Stark in favor of MODOK. Tony's a savvy guy, and I give him credit. But there's a point where you have to account for "so freakish scary smart that it's not smart, it's prescient." Tony's power of intellect is also informed by his ability to negotiate and be diplomatic. He uses those together. Besides Doom, no one up there is terribly diplomatic, possibly excepting Reed.

The "seeing in equations" power has been alluded to or described in other terms for Banner and probably Thinker, Leader, and Richards. Without Cho specifically citing the ability as something Banner/Hulk possesses (in the Incredible Hercules issues of World War Hulk somewhere), I might not include him.

There's a pool of really talented guys like Stark, T'Challa, the Wizard, Techno/the Fixer, Pym, and Hank McCoy who are knocking on the door. It's the non smart abilities they bring: diplomacy/negotiation, multiple areas of competence, stagecraft, mutant powers, and spousal abuse (couldn't resist) which let them leverage those smarts and be in the running.

Well, I'm the OP and the guy who posted the picture.

But they say Amadeus is 7th smartest a lot, not just in that picture. "I'm the 7th smartest person on the planet" is pretty much his catch phrase. I think the list of smart people was developed by Richards, by the way. I also think it's safe to say that Stark and Reed are higher because during world war Hulk they say something like "He's only the 7th smartest person" and look all smug about it.

Yeah, they've been referring to him as the Seventh Smartest Person on Earth since the character was introduced. It's a major part of his character. Though I sort of hope they never reveal a "Top 6" list, as it would end the whole conversation, which I think is the fun part.

1) Mr. Fantastic
2) Doctor Doom
3) Mad Thinker
4) Leader
5) Tony Stark
6) Wizard
7) Pym
8) Cho

Yes, but again.... Cho's now 10th According to Banner.

Also, Pythagoras Dupree was the sixth smartest person.

Saying that and being acknowledged that is two different things.

Of course, being the 7th smartest person on the planet still puts him behind all the dolphins and mice, sooooooooo, enjoy being the something millionth +7 smartest being on the planet!

yes but it's only 2 white mice and all the dolphins left so he's got that going for him

It seems to me when everyone(including the villains) talk about the 8 smartest people, they're basically talking about the heroes, with the exception of Dr. Doom who just stands out period!

People like Mr. Sinister, The Master, The Leader, M.O.D.O.K., Maximus, Thanos, Apocalypse, Dark Beast, High Evolutionary, The Jackal, etc. are all incredibly high on the list of villains with Doom being included on their side as well. For some like Dr. Octopus, he's a genius in the field of radiation. So much so that Reed Richards sought his help for the birth of his second child.

Dr. Doom, Mr. Fantastic, Bruce Banner, Black Panther, Hank Pym, Beast and Tony Stark are all above Amadeus Cho overall but, that still doesn't make him a slouch!

Mr. Fantastic
Pym
Stark
Doom
Beast
Leader
Mad Thinker

I thought when Pym came back after Secret Invasion he told Cho he was now 8th.

There's no "for sure" list, but we can narrow it down by actually thinking how it would work.
You gotta realize that, in story, Tony Stark, Reed Richards, and (skrull) Hank Pym probably came up with this list. They obviously are going to include themselves and their friends.
They obviously are going to exclude MODOK, Leader, etc., with artificially enhanced intelligence and being super-villains. They maybe would include Dr. Doom, because Richards and Stark have marveled at his intelligence before.

In a recent issue of Iron Man, Tony says sometimes he thinks Reed is the only man as smart as he is. The difference is Reed would NEVER think that about Tony.
Smartest human ever definitely goes to High Evolutionary, though.