Auto-translated
Of course, everyone has their own opinion, and you're right about that, Ley. But personally, I find that I play best with the Swamp Castle.
I generally agree with those who believe that there are no weak or strong Castles, just that you need to know how to use the advantages of each Castle and how to find all the weaknesses of your opponent. For example, the Stronghold, i.e., the Barbarians, also has many advantages: a good "offensive" specialization for the Castle, heroes, and creatures, the ability to hire a Ballista and a War Wagon in the same city, the Guild of Mercenaries, and the abilities of the creatures. But I play worse with this Castle than with the Swamp Castle, because it's easier to develop the economy with the Swamp Castle. Also, it's usually less problematic to get the wood needed to build a Wyvern Tower than to get 20 crystals for Cyclops.
In general, the Stronghold and the Swamp Castle are two opposing Castles. You could say that one cancels out the advantages of the other, i.e., Attack compensates for Defense. In my opinion, it's harder to play against the Stronghold with the Swamp Castle than with other Castles (all other things being equal).