Just think about it, maybe you'll figure it out :)
1. Castle. Stables in the castle. Minimum speed 6-7.
2. Rampart. Kiras. No question.
3. Barbarian - for example, I often have Gurny running at 112-113 already with group movement. This is very convenient and effective :cool:.
4. Swamp. Speed 9, or even 13 (it's not that rare to need to upgrade snakes in the first week, and it's a must in the second).
5. Inferno. Ifrits at 113-114, speed 9.
6. Conflux. Speed is often 7 from the start, and all horses have it. In the second week, often birds.
Heroes from these castles almost always run much faster than Necropolis heroes in real conditions. Fact.
Furthermore, Tower and Dungeon, these are not always faster than Necropolis, but often, Dungeon also has Gurny, by the way.
And the Necropolis has to run with its native speed of 6 in the first week and without bonuses, and in the second week, a maximum of 9, and even then, if the hero doesn't fall behind the chain, then either skeletons are discarded or they move very slowly. Any objections? :cool:
Added 9 minutes ago
If we are considering a SINGLE unit, then the Necropolis troops are NOT the STRONGEST, but they are definitely not the weakest! And since you are considering mass battles in SoD, in the second week, with average-weak distributions, Galran has about 500 skeletons even on CMs (this is by days 123-124), and it is almost impossible to break through this without a lot of luck with hives/cons. Judging by your sharp and unfounded statements, I only see a "complete noob" in you.
Added 6 minutes ago
Do you even read what I write? :) I'm not talking about the unconditional strength of the castle (by the way, what is that?), but about the strength of the castle in relation to specific game conditions.
The Necropolis is generally the strongest castle.