We all know that each shaft company ignores any standard of flex. In addition to that, each frequency machine is a bit different when reading that flex. Finally profile makes an impact on the readings received when measuring shafts.
When answering your question I would break this down into two categories 1) true to stated flex as compared to my machine and 2) profiles consistent to each shaft.
For me personally,
1) steel KBS, Graphite UST or Adila
2) steel KBS, Graphite AXE or UST
I don’t work with all the shafts and Britt is far more qualified that me to answer the question and would also add that you cant go wrong with Fuji, PX, Mitsubishi or Nippon either. I have had great results using them too,
Good comments. Thanks.