I completely agree: I've encountered stables MUCH more often at the Castle respawn than at the Necropolis one. If you add to this the difference in speed between skeletons and many Castle units, it results in a very significant head start for the Castle. This can lead to earlier scouting and exploration of the Dragon Utopia. The free cavalry upgrade in the stables provides a nice bonus + the prospect of upgrading "canned" angels in the home Castle is encouraging.
Overall, the Necropolis still looks slightly more preferable, but much depends on the specific features of the map. On many maps, the Castle has a chance.

Орден Феникса – харизматический :) лидер