Necropolis or Castle (Which one is stronger?)

In general, I believe that Necromancer is undoubtedly stronger. The main reason: hordes of skeletons. Additional reason: vampire lords. Other minor advantages, such as double strike, immunity to certain spells, etc., are compensated by the Castle's abilities.

It takes time to build up these vampires... in general, it's a long process.

Yes, it will be cheaper than the Portal of Glory, but more effective.

5. Water magic for Humans is a significant argument, plus leadership, but again, it's too much if...

Isn't it a significant advantage for Necromancer? For example, dispel and free teleportation – free delivery of skeletons around the clock to any location on the battlefield.

6. Morale for Humans adds a bonus to the Castle... in general, it's more likely that Necromancers will find the spirit of despair.

Morale is found quite often in crypts. The main thing is to open more of them.

7. Humans go first in battle and move faster overall, plus tactics are often available.

After mass haste, everything moves quickly. I wouldn't mind taking tactics for Necromancer either – the closer the skeletons are to the enemy, the better.

8. Humans move faster than Necromancers, plus stables, and I personally don't like the slowness of Necromancers.

If the Necromancer isn't using underground movement, then stables are often found on the dirt. And if you want to move fast, you need to accelerate with Nightmares or Serpent Riders.

9. Griffon Conservatory – a small plus in favor of Humans.

Necromancer has enough regular angels – and here is point 8 nullified – all that remains is to give the skeletons to someone else.

10. Diplomacy – it will also help Humans more than Necromancers...

I don't know what Humans will do with all sorts of rabble, but Necromancer will turn it all into skeletons. Diplomacy often provides Isre or Vidomina.

11. NECROMANCY – a huge and significant plus for the undead, which often outweighs all the small advantages of Humans)))

I believe in the balance of heroes and think that everything depends on the conditions of the map and the level of the players.

I completely agree with you on these points. ;)