From my experience:

Atlanta and it's remodels (Juneau especially, rotating the guns is a challenge though)
Brooklyn
Pensacola (my favorite since it takes advantage of the T slots) 

In the end I'm probably going to say it's the Pensa, just because it is highest in level of the options I posted up there. I use the 5"/38s on mine; quick fire rate, and fairly good damage. 

Best in terms of performance is Brooklyn with aa on R slots. Good speed, lots of ammo and guns, and you can carry a scout. Pensacola is ok but the Tslots are small.

USN aa is not great though, I would reccomend getting a pair of KM or IJN aa gunners if you plan on spending alot of time AAing.

Pensacola (the T slots are close together allowing blocking of the 3"/70s)(360 gun rotation), Lack of T slots, (8 Total) The close grouped T slots allow easy AAing as you don't need to cross guns. ) Rating: 8

Brookyln: Can run 4 different AA setups effectively. 6"/47 Dual DPs, 5"38 Cal Mark 38s, 5" 54 Cal Mark 16s, 3"70s. However limited by the Gun rotation. Also spacing between Forward and Aft guns makes you need to cross guns more. Great gun space, you'll never run out. Rating: 7

Omaha R slots setup allow great forward AA when chasing planes. It has 9 R Slots, however it can only use the 3" 70s due to the Superstructure turrets lack of gun space. ack of ammo aswell. 10 binds in all but the front and rear turret with 30 binds. Runs out of ammo but a great ship to get sailors from lvl 1 to 30 for the Atlanta Classes. Rating: 6

Atlanta: Great AA ship minus the extra 2 guns in the middle of the non-remodel. I suggest remodeling to the Jun or the oakland. The ship is fast and turns quickly but has a horrible fireing arc, making it hard to track planes for long periods of time. Can effectively use the 3"70s, 5" 38 cal Mark 38s and the 5" 54 Cal Mark 16s. Rating 7

Nebraska (well I'd rather you use it as a BB lol): Excellent T slot battery with 14 total turrets, a broadside of 14 shells per side with any US AA Gun, 6" DP Usage requires lvl 115  AA gunners classed at, well level 115. Rating 10

Midway (Again rather use it as a CV lol): Superb R Slot battery of 9 turrets per side, a salvo of 18 shells. Can use every A variant gun and every 3 and 5" regular AA Guns. Again needs 115 gunners. Rating 9001

Be forwarded, US is not a powerful AA nation, however it does have the best damage per shell for its gun sizes (Excluding the 5" 54 cal Mark 16s).3" can one shot T4 and down scouts, 5" can one shot any if hit right plane and so can the 6" guns. You range will suck as well for everything but the 5" 54 cal and 6", but still will shorter than most nations.

brookly and pensa. 

Pensa: 360 degree T slot spin, but ammo may be an issue in long games. 

Brooklyn: you'll never run out of ammo, however, since it is on the R slots, some time is lost when turning the ship around or turning the guns around.

atlanta/oakland: not bad, but like other said, i'm definitely not a fan of the gun angles of the ship

Brooklyn with 6"47DPs works quite nicely IMO.

midway

no doubt 

I dont use the extra guidlines for USN myself. They just clutter up the screen and if you were to start relying on them you would hurt yourself when playing other nations.

Turn off the extra guidelines when you play USN AA. They're a waste of time.

USN AA suffers from the lack of range, which speed can somewhat help cope with (Warn you, it doesn't help with the risk of being one-shotted when the planes are far outside the battleline). Therefore I recommend the following:

1. Pensacola. The superb speed and excellent T slot placements are simply perfect. It is the fastest thing of the USN if used with engies in the support slots, and is still fairly fast when the said slots are used for grinding other stuff. The only disadvantage of the Pensa is that it is a premium ship, but if you plan to play USN seriously it is well worth it.

2. Omaha. Poor gun slots, but at least you have a decent firing arc (Yes Atlanta I'm looking at you) and excellent speed (40/49 with ease without engines).

thx