The passwords in the files are sorted by predicted frequency of usage, in descending order. It means that if you have limited time, take the part_1.txt as your wordlist. If you have more time for a bigger wordlist, please combine them like
cat part_1.txt part_2.txt part_3.txt > wordlist.txt
The number of passwords in each file is as follows:
10000000 part_1.txt
20000000 part_2.txt
20000000 part_3.txt
20000000 part_4.txt
30000000 part_5.txt
20000000 part_6.txt
120000000 total