Definitely one of my favorite mechanics. I’ve sunk countless hours and dollars into Dominion and the OG Thunderstone. My favorite aspects are the engine building aspect and, for games with fixed markets, coming up with the winning build strategy against my opponent(s).
The best deckbuilder I’ve played recently is Helionox. There are a lot of reasons to love the game but, focusing just on deck-building, it is the combination of placing purchased cards on top of your deck, having the option to always bury one of the top cards on any of the 4 markets, asymetrical player powers, having a draw size independent of the hand-limit (you always draw 5, then discard down to your hand size), and having a card function that allows you to pull cards from your deck that make this the most satisfying deck-builder I’ve played. None of these are necessarily “new”, but the combination allows you to build, optimize, and enjoy your engine throughout the game.