Thats cornflower though its just the same there is no quality difference, supermarket own brand super strength lager is economical, see its cheap plentiful and gets you pissed fast; yet i highly doubt id choose that because the quality is low and im not a "jakey". I would assume the same applies to thermal paste if you don't need a large amount you can spend less and get better stuff. Another analogy is like comparing pva glue to super glue, you get more pva but its weaker.
Get the Ceramique then since i guess you made your mind up, but id get the MX-4 because it seems pretty good and its better than MX-2 and MX-3 which i know are better than AS5.