From my findings (maintaining the
ircd.botbay.net ircd archive and writing IRC services programs), I've come across the following "statistics":
csircd (
cs-ircd is something totally different) is rarely used on non-EFnet networks. I personally run an instance of it on an ircd/services test network, but I would not personally use csircd in a production environment.
Hybrid 7 and ircd-ratbox have a fairly even share of non-EFnet networks, with the larger networks and the EU networks (minus Bulgaria) gravitating towards Hybrid, and the smaller networks and most of the Bulgarian networks using ratbox. A number of these networks use modified versions.
Hybrid 6 is truthfully a different ircd than Hybrid 7. The name is the same but much else is different. There are still a few networks who remain using Hybrid 6 and modifications.
Also remember that ircd-ratbox is much newer than Hybrid or csircd, so the name is less known to networks outside of EFnet.
If you wish a more objective opinion, or wish to look at things yourself, the following sites can help.
xgoogle (when it was up) allowed you to search according to ircd versions, and this, as well as browsing the server lists on
netsplit.de is a good way of seeing "statistics" on what other networks use.
SearchIRC refuses to include ircd information in their site, so don't bother looking there for finding servers running Hybrid/ratbox/etc.
Browsing the above sites could help you gauge the popularity of the various servers, but as with everything, remember that they are skewed. There are many networks not listed on any of the IRC search sites, and there are many networks who change the name of their ircd, making it harder to tell (without connecting to a server on that network) what specifically they are running. There are also networks who change ircd's frequently.
Browsing message boards where networks announce news or look for links can also help (and will include some of the smaller networks not listed in xgoogle, searchirc, or netsplit.de). Two fairly useful ones are
SearchIRC's boards and
ircd.cc. Note that you will have to pass over hundreds of posts about unreal and bahamut networks to get to the ones using an EFnet/TSora protocol ircd.
It could be interesting to ask those networks WHY they chose the ircd they did, but I don't think the EFnet forum is the best place for it.