system
Given the following post, respond as if you're commenting on Reddit:
human
[Phineas and Ferb] Who is the smartest?

Who’s the smartest person shown in the series?

Phineas and Ferb seem to be equal, with Ferb etching it out solely because of his high social intelligence.

Baljeet is shown as the smart person of the group, becoming a professor as young as 17-18, but at the same time needed help from Phineas and Ferb to build a portal. Also he just doesn’t feel as smart as them aside from what the show wants us to believe.

Doof is another contender building -inators that casually break the laws of physics, although that does also apply to Phineas and Ferb.

Isabella and the Fireside (and Buford too) girls while not serious contenders also are shown to know how to help build, repair, and use the devices that Phineas and Ferb build. Isabella especially, in the recent movie she was coming up with ways to increase the speed of the Spaceship.

Who seems to be the smartest out of all of them?
gpt
They're all intelligent in different ways, which is hard to measure.

Phineas and Ferb are Renaissance Men; genius engineers with an instinctive and intuitive talent at almost everything they attempt. It helps that they're such a close-knit duo, since they're essentially putting the minds of two prodigies to work at everything they do. It's hard to guess what they'd accomplish when alone, since they're almost always a package deal. Their sheer range of skills and disciplines probably edges them out as the most impressive of the group.

Baljeet is likewise a genius, but it comes to him a little less naturally (hence his constant studying), and he probably excels more at academia than at physical engineering; Phineas and Ferb are like flashy trailblazers, but it wouldn't surprise me at all if Baljeet is the one who does the legwork to make sure other people can later understand and replicate it. Building a space elevator is cool, but writing a paper on the engineering used to create said space elevator so that all scientists can later replicate that feat of engineering is even cooler.

It doesn't come up often for Buford, but he's actually a *creative* genius. He'd trump the others if it came to writing poetry, or directing a film, with only Phineas and Ferb really being able to come close. 

Isabella and the Firesides girls are the best within their niche; they're mostly not genius-tier engineers like the others, but have brilliant minds for problem solving within the constraints of a situation, as well as a lot of knowledge about survival and various useful skills. Plus, they're the most likely to be able to kick your ass.

Doof is a brilliant scientist capable of breaking the laws of physics, and is also a complete idiot. Where Phineas and Ferb are very well-rounded, he's good at only one thing. Even basic common sense tends to elude him. He'll create a machine that's an engineering marvel to solve a problem that could be fixed by parking his car five feet to the left.