OK, here's a better list of the top servers. I removed a few more that were only up for less than a day. The "Record Count" column represents how many stats I have for the server which is taken once per minute.
name average_players max_players utilization record_count
n00bstories.com AOW/CCM 37.6380 40 94.095 75891
n00bless.com All Out War 24.3339 32 76.0434375 73816
Jelly-Server [Mini AOW] 13.5998 20 67.999 44919
www.Jelly-Server.com 25.4129 42 60.50690476 108959
Fnfall's AOW Server 17.9689 36 49.91361111 75676
~XpHaZe Marathon~ 15.6018 32 48.755625 35545
[DS] Black-Cell.net - Marathon 15.5271 32 48.5221875 75766
Fnfall's Marathon Server 17.1150 40 42.7875 73412
UNRULES.COM - New Maps 17.0991 40 42.74775 75446
Fan-Maps.net - CoOP 6.1347 15 40.898 43459
The stats for Jelly are messed up because they had both their AOW and mini AOW named identically which resulted in fucked data. In fact their utilization is definitely a lot higher. If I can figure out when they fixed the names, I can find a more accurate utilization stat.