Gonna go ahead and say you haven't played it enough for that to be your opinion.
Hmm no. I'm 2 for Silent and 2 for Ironclad. Comparing both runs, Ironclad + whirlwind was the easiest but that was a matter of some really lucky rolls and teching really hard into supporting whirlwind really early. I would have been 3 for Silent but i didn't plan out my fight against the The Time Eater so i kept hitting his 12 cards cap without realizing it. The most abusive decks for Ironclad are the most high risk, so you either win hard or bust in the exact moment you don't expect.
I'm Ascension 13 Ironclad, Ascension 3 with Silent. Schild is correct. The most effective deck in the game is snecko eye with a bunch of 2-3 cost offensive cards. Cut all defense.
"My great-grandfather did not travel across four thousand miles of the Atlantic Ocean to see this nation overrun by immigrants. He did it because he killed a man back in Ireland. That's the rumor." -Stephen Colbert
I'm 7 with Ironclad and 8 with Silent but that's only because I put a lot more time into Silent. Silent is harder. Ironclad has a number of standout cards that work well in most builds. Silent has a lot more variety which makes it more fun for me but the downside is you might not be sure of what kind of deck you're making until you've finished the first floor or possibly even later. Most of my best runs on Silent were due to a lucky combination of Relics that I could never foresee, whereas you can get a couple Perfected Strikes early on Ironclad and have the start of a strong deck.
Also if you make a deck focused heavily on Shivs and run into Time Eater at the end you're likely fucked.