Ideas and suggestions.

I think if you offer opponents to pick Dungeon against your Stronghold/Tower/Castle, there will be no shortage of takers, even without a reroll, and even more so with it...

in the current reality of Heroes, these castles are roughly equal and depend on the situation, and Dungeon will indeed be popular for a while, until players have played at least 10 games with that castle.
If I had to give a rough estimate, Tower-Dungeon would be 45%-55%, Castle-Dungeon 55%-45%, Stronghold-Dungeon 55%-45%, in my opinion.

Regarding Swamp - well, I don't know, Dragon is good, but calling it top-3 seems a bit optimistic to me. Suggest to your opponents to pick Rampart against your Swamp - I think there won't be any refusals either.

Dragon is very good, and with good map awareness, it's a pleasure to rush with it. (It clears out objects almost faster than anyone else).