Heavier, faster, better written riffs than there predecessors....Originality is important...If a band can not be original, it want least a attempt for a band to create something that is there own. I also look for albums with no filler tracks, songs written to fill track order space...aka songs for the sake of being songs.
Thinks like authenticity are important. With songwriting If I can not remember the music, after sending 3 weeks with it, and I can not remember the whole album goes to "return for store credit pile".
But I usually avoid these return to store credit situations, buy avoiding over-hyped bullshit in the first place. I collect according to what albums that will survive the test of time. It is not rocket science to find albums that are timeless classic.