Browse the forum of past threads and see what you like because everyone has different tastes. There's no rush to get a 2nd PAM so soon but some are bitten by the Panerai virus so bad that some already look for their 2nd one right after they get their 1st! Crazy ain't it?
If I were in your shoes, for your 2nd PAM, I'd either consider a 44mm Luminor (non submersible model), a 47mm 1950 Luminor, or a Radiomir 45mm or 47mm. Panerai has plenty of models for everyone so take your time and wait for the one which makes your eyes sparkle.
Cheers,
Anthony