I haven't played a league that deep in quite some time, but looking at your assessment, I'd say that 20 teams is adequate. Obviously, adding another team could make things interesting and that team could end up competing for the title, but 20 teams seems fine. Also, if people are complaining that the league is unbalanced, then something needs to be done to ensure that you don't lose the members that you have. If that means sticking with 20 teams, then stick with 20 teams.
Yes doctor, I am sick.
Sick of those who are spineless.
Sick of those who feel self-entitled.
Sick of those who are hypocrites.
Yes doctor, an army is forming.
Yes doctor, there will be a war.
Yes doctor, there will be blood.....