Well, it should always be your Top 20, the 20 you like the most. for this list here, as well as for the other list:
The difference of the alternative Top 20 is only that the first 18 of the Official Top 20 are not allowed. The reason is to see if in such a list other films are named than those, which are in the official Top 20 behind the first 20 (or meanwhile actually behind the first 18).