Lots of differences between the different flats out there, Jazzy.
I really liked the T-I Jazz Flats on my Persuader 5-string, (has a P/J setup) but I switched to the Jazz Rounds this past year and really liked the expanded range of bright tone. I still have these on my Custom fretless, modeled somewhat after the critical specs of the Persuader. A lot ot players hate the ultra-soft tension of the Thomastik strings, but it just feels right to me.
I hear good things about the LaBella low tension flats lately. Haven't tried them, personally.