I've used AF-78 like it says in the Wiki to pretty good success. Only problem is the weather is always hideous - at least for me between September and January, as I'm still new to the game. Which means no deck gun, which means letting some little boats go to save the torps for something worthy.
AM52 has both single ships and large convoys. I even saw three luxury liners running flat out accompanied by four large escorts, but they were making way too much steam for me to catch up with them.

Must have been well over 100,000 tons across the three of them.
I wonder - if you take out a big liner's propeller and strand him - do the escorts hang back to protect him, or abandon him?