THIS!
For me "balls" in a Jazz Bass is all about the Ged. Fresh strings and low action on a flat skinny neck is the name of the game IME. After decades of trading I'm not even buying any fretted bass that's not like that. I love the "moody" variation of every vintage tone (P, Jazz, Musicman, RIC), aggressive and barking on XXI century playability. The fresh strings + low action + fast neck thing is 50% of it, and it in turn stimulates the other 50% that's my playing, it encourages me to play "at the service of the setup", digging in the ultimate orgasmic "raspyness".