POT is heavy as fuck and the majority of it is thrash. It may be different than ATL but still has a signature Athrax sound. Sure Belly of The Best might not be the heaviest Thrash song. But I'd say songs like Time, Discharge, One Man Stands, Got The Time, Keep it in The Family, etc are definetely thrash.
I don't like much from SOWN. Songs like Only and Black Lodge make me i'll. When Only was released I felt like I just got kicked in the balls. Anthrax would never be the same. Is that a 'good' record. Sure, its written well and produced well. But that was the gateway to Anthrax turning into an average sounding generic band and started the demise of the band. But luckily it appears they may have finally figured it out 20 years later. We shall see