With Ironclad, I really love when you get a good strength build going. Demon Form early game is so cash money
With the Silent, Poison builds are my go to, but if you get a good something going with Shivs in the beginning, it's so much fun.
The Defect, I recently defeated A3 with a channel lightning build - where you channel for every time you get hit. I was channeling, i think 6 every hit and had +4 focus, so when the heart did the 4x12 attack, it destroyed itself. Felt incredible.
I haven't yet figured out a solid strat for The Watcher, but divinity is fun and I enjoy going full wrath, but having enough defense to back that up proves difficult.
In terms of similar games, if I'm feeling a little more casual/braindead, Peglin is a lot of fun with a similar deckbuilding style. I have yet to figure out any really good builds and I think some balls are definitely better than others, but it's still fun and super casual.