I once owned both the 4U JS12 and 4U JS12ii at the same time, but later sold the JS12ii and still use the JS12.
The JS12ii does have a slightly weaker smash compared to the JS12. Both rackets are better Front to Midcourt rackets. The JS12ii does have the upper hand in handling the racket vibration due to the ‘Freecore’ which IMO is a pretty revolutionary technology because of how well it dampens harder feeling strings like BG80 which might be a little unpleasant for some players.
I actually think the JS12ii isn’t an upgrade from the JS12 but more of a sidegrade. Because of the freecore you can’t really ‘feel’ the shuttle for those controlled shots.
I think a racket that might fit your requirements is the 4u Victor Thruster FE or a 3u Victor Auraspeed 100x.