with hydraulic brakes there are a number of variables.
1. The brake being bled properly, or not.
2. The age/condition of the fluid.
3. The age/condition/material/etc of pads/rotors.
With Sram Brakes Avid juciy 3/5/7
Juicy, Elixer, Code etc.
the higher the number usually the nicer the brake, how much nicer, how noticeable, how worth the money? thats up to you