I would go $20 pre; $15 is clearly too small
X flop four ways ainec. My betting range on this flop is TT (only set I raise pre), all of my flushes (which are just suited broadways), and then my A
combos (A
Kx/Qx/Jx.) There's no reason to bet JJ here; we can't get value from a whole lot worse, but still have decent sdv.