Tibiaking and Otland is the biggest, then I guess torg.pl is quite big for polish people too. There is *****.net and opentibia.net (old OTFans) but they're pretty much dead and used by nobody.
https://www.google.se/trends/explore#q=otservlist, tibiaking, otland, otfans&cmpt=q&tz=Etc/GMT-2 As we can see from this otservlist is clearly much bigger than any other side
Then there's reddit (
http://www.reddit.com/r/tibiammo,
http://www.reddit.com/r/tibia) and twitch that you could also use to promote your server somehow. It seems very hard to advertise servers in general without using otservlist's "starting soon", like there's a lot of beautiful threads here on OTLand but sadly I think that the community is just too small to get lots of feedback etc on your server and the owners expect a lot more than they get so it usually ends up with them giving up on their projects. I mean even necronias thread is pretty dead which is a project that should attract almost everyone interested in open tibia. For example some threads:
https://otland.net/threads/delyria-evolution-10-79-discussion-thread.230652/ - pretty much just the owner and 5 people talking about it
https://otland.net/threads/7-7-cipfiles-discussion.225985/page-8 - quote from owner "I felt no urge to work on the server whilist the interest was so low"
https://otland.net/threads/hypia-net-discussion.228059/ - again just like 5 different people commenting and showing interest
https://otland.net/threads/discussion-thread-ruthless-chaos.229141/ - a lot of nice and big comments but just a few different people showed interested in the server too
There's also
@Printer 8.0 server that had a really nice discussion thread but when the server finally came online pretty much noone showed any interest and I believe that the project is dead now too
There's lots of threads like this with promising servers that never seems to get finished and I would think that most of these projects got abandoned because of lack of interest from the players and the community (what
@Ecstazya said in his thread)
And then there's projects that just put their servers up on otservlist.org advertisement for a couple of days and gets hundreds of players solely because of that.
Here's some more thoughts on the "starting soon" feature:
https://otland.net/threads/otservlist-starting-soon-and-resets.229287/