I've been on a bit of a break cue search recently, tried some cheap chinese breakers, players, j&j, spark, will move up to some better brands soon including carbon after I try out a couple more cheapies (Rhino and Billiards warehouse house special)
fwiw, in the meantime best results for me have been with my playing shaft, 12.5 cynergy and stock tip
my break speeds as measured by the app are slightly higher with this cue and i can consistently hit the headball more accurately, closed bridge on a long pro taper so no surprise there, and generally better cueball control
are there other factors other than cueball speed that can cause a rack to "spread" better?