Tom Holland is an amazing Spider-Man but he isn't the Amazing Spider-Man. Andrew Garfield is the best Spider-Man. He just is. Even if you can make a case for Holland (and Spider-Man: Homecoming was great), you definitely can't for Tobey Maguire. The strongest argument can only be made for Garfield.
Seriously, the only thing worse than Emo Spidey is the James Cameron version of the character that mercifully never came to be. Better than the worst possible scenario, doesn't mean the best. The Amazing Spider-Man is widely considered one of (if not) the best comic version of Spidey. Nobody embodies Peter Parker like Garfield, certainly not the improbably old Maguire, and Holland's just a wee bit too twee. Garfield is the truly the only reasonable option for the greatest Spider-Man of all time.
Garfield's Peter Parker Had Way More Character Development Than Maguire Or Holland's
The MCU decided to skip over Uncle Ben's death, because the audience has seen it ad nauseam and knows the story. Still, it is the single most important moment in Spider-Man history. It was the moment a hero was forged. We got no such moment with Holland's character. That's not his fault, but it is the reality.
Maguire did have his Uncle Ben moment, but he didn't have an Uncle Ben AND Father Parker moment. We watched Garfield deal with two tragedies, and we saw more anger in him that had to be harnessed into heroism. Maguire had an angry moment, but it wasn't as believable given how cheesy he can be, and his anger burned away much more quickly than Garfield's did, making it less relatable.
Garfield Is The Best Actor Of The Three
Maguire has been nominated for one Golden Globe, while Garfield has been nominated for two, and an Oscar, despite being eight years his junior. Holland may still earn major awards, but he hasn't been nominated for any. So, if we're going purely by awards recognition, Garfield is the best actor of the three, empirically speaking.
Garfield's Character Was A Hero Before The Powers
Early in the first Amazing Spider-Man, Peter stands up to Flash as he's picking on a kid, and ends up replacing the hapless student as the subject of Flash's torment. While we see Maguire's character lament his inability to standup for others before he gets his powers, we actually see Garfield take action, proving heroism is defined by more than superpowers. Garfield's Parker possesses more inner strength than Maguire's.
Garfield's Spider-Man Humor Is Spot-On
Peter Parker is supposed to be kind of nerdy and self-conscious, but another, equally important, element of his personality is his smart mouth. He slings quips with the speed and accuracy of his webs. Maguire's character got none of this. He was basically a shy nerd; any humor around his character was around his character, so we were laughing at him, not with him.
Holland is much better than Maguire, but most of his humor is couched in childish glee and/or awkward stammering, again because self-doubt seems to be his overriding character trait. While he's a bit more quippy than Maguire, he's still not quite as developed as Garfield. For example, when Garfield's Parker catches the thief who killed his uncle, he toys with him, sticking each of his limbs to a wall sequentially. That's classic Spider-Man humor.