Theoretical a mix of all options would have served best.
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I think two medium Aircraft Carriers would have had an imense impact on the Battlefield of the Atlantic and the Med´s. German Aircraft carriers with a old of 25-30 Planes.
The British focus would have been on the CV´s first to even get through to the Subs.
CV´s proved to provide a bigger threat rather then Battleships but needed a bigger household and logistic.
For German use, all they had to do is to patrol up and down from the E-Channel down to Gibraltar.
Gibraltar taken with a swift blow of the Fallschirmjägers, Airsupport and Naval Support ,as soon as the first German CV is on duty.
Italien support would have been a must.
This could be a possibilty only, If Germany decided not to engage in an Airbattle over England.
If Germany only had like 100 to 150 operational Subs combined with enough Airsupport in coastal area would allready create a greater diffrence to the Atlantic Battlefield I think.
(in CV´s converted, Thank you)