pluque

Hey guys, I have an xt-5 with xf33 and xf16-80. I maybe planning to buy a xf70-300 as well eventually. But for now, Im looking for an all around ND filter, you know one that might fit most of the situation. Im not looking for a variable, or maybe I should, but anyway. If I had to buy only one ND filter, considering that i already have a CPL, what would you go for ? thanks in advance :D for your input all!