That's right, VanessaEs servers are very stable. Buildings from her very first creative map where all copied over when the map was changed to a newer one a long time ago. Those are servers where builders are welcome and can truly feel at home. The servers suffered a bit lately due to a bug in the engine and some over-automatization IMHO, but are still the most attractive ones for builders. There are machines which create all materials for free in huge quantities on the survival server, and the reactors are not the nicest constructions to look at (well, atomic power plants seldom count as art in RL either). Perhaps the creative server might be the best choice. As far as survival goes, RealTest is far more of a challenge than normal MT.
And then there's still Redcrabs server. It does still work. Sadly, recent clients can only connect to it if their cache is cleared before connecting, and the server does not show up on the public list (redcrab.suret.net 30401). Redcrab shows up extremly rarely, and yet the server runs quite well - and has over more years than any other server.
Other servers that have been up for a long time and where builders and their creations are treated well are linuxgaming.us and King Arthurs Land. Your constructions are safe there.
Avoid servers that do not have a protection mod or rely on the protector mod. It has proven countless times to be insufficient for the needs of creative builders, and the server operators who use it mostly don't care enough. There are some concepts that work - either rollback or some internal alternative has to be present (whitelisting/backups/alternate rollback as on VanessaEs servers and King Arthurs Land), and the server owner needs to know how to operate these. The servers mentioned above are save in that regard. Even Redcrabs server - provided you protect your area.
If a server which hasn't been around for a long time and which may not even have the areas mod installed has a nice spot somewhere or very attractive textures, by all means enable
Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.
in your minetest.conf so that a local backup of the world will be created on your disk.