Depends on the weapons mix.
The Iowas were exceptionally good at the escort role (realistically the Iowa and her sisters were BC to the never built Montanas BB. Whether they were the best choice for the role is a different question. IMO they were not.
The Iowa class ships cost $100M+ and required a crew of over 2,700. For that same construction cost the USN could have obtained FIVE CLAA, for the same manpower they could have operated four CLAA. The Iowa class carried 10x2 5"/38, the best naval AAA weapon of the war, a total of 80 40mm (in a mix of dual and quad mountings, the effectiveness of the 40mm remains a subject of some debate) and 40+ 20mm (a weapon that was more or less a last ditch point defense weapon that could not assist in the defense of the carriers).
Each CLAA mounted either 8x2 or 6x2 5"/38 (early ships had "wing" turrets that were not carried forward in the second batch of hulls), 8 40mm, and 14 20mm. For the same cost as one Iowa the fleet could have gone from 20 to 60-70 of the 5"/38 (by far the most effective AAA weapon available), albeit at the cost of 50% of the battleship's 40mm capacity.
There are, of course, other considerations beyond pure firepower that fall on the capital ship's side of the ledger these include survivability and the ability to act a force flag and/or communications hub. You could, using the displacement of the BC possibly come up with a design scheme that would get you many more heavy AAA mounts, although at the cost of the heavy gun scheme.