You won't use the low-cut on a jag if you get one.
Jags and Jazzers have similar tonal charactaristics- plinky surfiness, lack of sustain. Jag has marginally less sustain due to shorter scale length.
Jag pickups are brighter, Jazz0r pickups are warmer.
Jazzmasters are more versatile. People only buy Jaguars because of all the cool chrome (or stainless steel, if you're going japanese).