I would venture a guess that the Endeavor would be better. With a Hangar, Fuel Pods, and Telescope pods I think it'll probably be the best.
Being able to fit smaller exploration vessels inside the hangar and detaching the front cab gives it a breadth of scope and range unseen by even the Carrack. You can even bring your own short range fighters to help defend.
Imagine launching 3-4 315ps for the sole purpose of scouting a planet, collecting samples, and returning them to the front cab. Anything they find that's too big the front cab can investigate itself.
I would agree that the Endeavor does have the on paper prospect of being a hub of scientific exploration. But I am not sure it will be overall better just like the Carrack wouldn't necessarily be used for forward scanning of enemy movements a role mostly given to the Terrapin. The other consideration is ships like the Polaris will also have a capital size radar which might make it just as capable.