How much of a difference does the amount of GB and Mhz of RAM do [closed]

I am thinking of upgrading my RAM for my computer and I am struggling to choose the Mhz and GB’s. How different would it be if I had a 4 computers, one with 2666 Mhz 2 x 16GB, 3000 Mhz 2 x 16GB, 3200 Mhz 2 x 8GB, 3600 Mhz 2 x 8GB. I have found these all in my price range. They are all crucial Ballistix desktop gaming memory.