The Essex class of carriers was, though you may argue that point, in my opinion the best weapon in the world when commissioned, and stayed the best carrier class until the Midway class became available in October of 1945.  

    The Essex class was the successor of Hornet. Just as Hornet, it was designed after the limitations of the Washington Treaty were lifted in1936, and it was thus not necessary to obey to any rules other than those dictated by common sense. As a result, a class was devised which was to follow five main rules:  

1. They were to be able to carry four squadrons of 18 planes, plus another squadron in reserve.
2. They were to be able to launch and recover planes faster than usual.
3. The were to carry 25% spares for her planes, as it was thought that US carriers would stay longer at sea than her counterparts.
4. They were to be survivable in combat and able to serve a long time.
5. They were to be upgradeable.

Each of these rules was followed. When USS Essex was commissioned into the Navy in early January, 1943, the US Navy had received all it had wanted. The carrier was able to carry up to a hundred planes, and, due to a aircraft lift to the port side of the flight deck, she was able to recover her planes while storing them in the hangar, and likewise for launching.  

    The ships were also highly survivable. During the two years the Essex class saw service in the Pacific, none of them was sunk, not even under the worst circumstances. This includes the devastation of USS Franklin, hit by two bombs off Okinawa in March 1945, during the preparations for the landing there. She suffered horrible fires aft, destroying planes and exploding "friendly" bombs. With 724 dead and 265 wounded, the carrier's captain was given permission to abandon the ship, but refused and saved Franklin. Bunker Hill, Admiral Marc Mitscher's flagship, was hit by two Kamikazes in May, 1945, and survived as well, with 389 dead or missing, and 264 wounded.
This may be to a great part attributed to the reluctance of the crews to let their ships die, but also to the rugged construction inherent in this class.