I think there's common human psychology that the
tracker(s) whose invite is hard to get will be more awesome as compared to others. But I think Filelist,
TD,
IPT may have more learning content than BitMe etc. but it's hard and invite is through staff only makes virtual HOAX and people follow each other and join the queue of sheeps'.
P.S: nCore and
TsH are also underrated. (as for me)