I'd argue that the US Independence class were fast escort carriers while the Colossus/Majestic class were slow fleet carriers. The British ships were definitely the better carriers.
I think the problem really is
nomenclature here. Which I think
@RamscoopRaider gets to the nub of:
The Independences operated with the Fleet rather than escort forces for their entire WWII careers, so they are light fleet carriers. They have the same tactical/operational speed as the big girls, they are just smaller with smaller airwings, less toughness etc.
It's all a question of what each Navy wanted out of these carriers. For the US Navy, what it wanted were carriers that could operate with the fast carrier task forces, especially in the vast expanses of the Pacific. And what it also wanted (as
@RamscoopRaider rightly says) were carrier decks it could get hold of
fast, as in, 1943! The
Essexes could only be built so quickly, even by the monster that was 1940's US shipbuilding. The
Independences were
not great carriers. They were cramped and lacked adequate protection. But they
did fit the US Navy's needs. They got the job done, and they got it done when it needed to be done.
Whereas what the Royal Navy seems to have wanted were really glorified escort carriers - not flattops that needed to operate with the fleet carriers, but carriers that could do convoy escort and ASW . . . and, eventually, to serve as maintenance carriers. So speed was not important. In these roles, the
Majestics and
Collosuses got the job done. (The
Centaurs are harder to evaluate, since none were finished during the war.) Really, though, in a USN perspective, they amounted to somewhat oversized escort carriers, and if they had been forced to use any, that is how they would have employed them, working alongside the
Bogues and
Casablancas.
So what is a light carrier? It really depended on who you were asking in the 1940's.