In my opinion, Tu-2 is about the supreme CV killer since it's introduction. While it is quite weak defensive wise, due to the generally low altitude in cv bombing other bombers are almost as likely to die if a proper cap is place. The Tutu is very quick to get in and drop drop two big eggs on the CV and one on the CA. The 1000kg have a great balance of punch and damage radius, so you have a good chance of sinking both capital ships, often in a single approach.
The only thing more awesome to use as a CV killer is a formation of B-29s. Three times four 4k cookies...