usefulness of the high-end Construction summons?

[Crevan]

My choice:
1. Mechanical Men. Resistant to many spells, cheap, quite effective in mid-game
2. Iron Dragons. Flying, fast and brutal. Useful for "attack rear" and killing of enemy mages. Or trample enemy archers. Or (kind of fun) some of them with Gift of Reason can quickly capture provs, which left unprotected
3. Siege golems. Sometimes they are the only way to capture enemy castles (e.g. longplay vs MA Ulm "Defensive" - he will build his damn Castles everywhere, but with Siege Golems there`s no troubles)